Neurobiology of Aging 36 (2015) 2004.e9e2004.e15
Contents lists available at ScienceDirect
Neurobiology of Aging journal homepage: www.elsevier.com/locate/neuaging
High frequency of beta-propeller protein-associated neurodegeneration (BPAN) among patients with intellectual disability and young-onset parkinsonism Kenya Nishioka a, Genko Oyama a, Hiroyo Yoshino b, Yuanzhe Li a, Takashi Matsushima a, Chisen Takeuchi c, Yoko Mochizuki c, Madoka Mori-Yoshimura d, Miho Murata d, Chikara Yamasita e, Norimichi Nakamura e, Yohei Konishi f, Kazuki Ohi g, Keiji Ichikawa g, Tatsuhiro Terada h, Tomokazu Obi h, Manabu Funayama a, b, Shinji Saiki a, Nobutaka Hattori a, b, * a
Department of Neurology, Juntendo University School of Medicine, Tokyo, Japan Research Institute for Diseases of Old Age, Graduate School of Medicine, Juntendo University, Tokyo, Japan Department of Neurology, Tokyo Metropolitan Kita Medical and Rehabilitation Center for the Disabled, Tokyo, Japan d Department of Neurology, National Centre Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan e Department of Neurology, Kyushu University Hospital, Fukuoka, Japan f Department of Neurology, Yotsukaidou Tokushukai Medical Center, Chiba, Japan g Department of Neurology, Hyogo Prefectural Amagasaki Hospital, Hyogo, Japan h Department of Neurology, Shizuoka Institute of Epilepsy and Neurological Disorders, Shizuoka, Japan b c
a r t i c l e i n f o
a b s t r a c t
Article history: Received 6 November 2014 Received in revised form 22 January 2015 Accepted 24 January 2015 Available online 30 January 2015
Neurodegeneration with brain iron accumulation (NBIA) is a genetically heterogeneous disorder, characterized by the accumulation of iron in regions such as the basal ganglia. We enrolled 28 patients with childhood intellectual disability and young-onset parkinsonism (40 years at onset) and 4 patients with infantile neuroaxonal dystrophy. All had been clinically diagnosed, and the prevalence of genetic mutations linked to NBIA (PANK2 [exons 1e7], PLA2G6 [exons 2e17], C19orf12 [exons 1e3], WDR45 [exons 2e11], COASY [exons 1e9], FA2H [exons 1e7], and RAB39B [exons 1, 2]) was evaluated. We detected 7 female patients (25.0%, 7 of 28) with de novo heterozygote WDR45 mutations, which are known to be pathogenic for beta-propeller protein-associated neurodegeneration. All 7 patients had common clinical features. Pathogenic mutations in other NBIA genes were not found. We also screened 98 patients with early-onset parkinsonism without intellectual disability and 110 normal controls of Japanese origin for WDR45 mutations. None had WDR45 mutations. Our data suggest a high frequency of beta-propeller protein-associated neurodegeneration mutations in the Japanese population. Ó 2015 Elsevier Inc. All rights reserved.
Keywords: Neurodegeneration with brain iron accumulation Beta-propeller protein-associated neurodegeneration Parkinsonism Intellectual disability WDR45
1. Introduction Neurodegeneration with brain iron accumulation (NBIA) is clinically characterized by brain iron accumulation in the basal ganglia and other brain regions (Gregory et al., 2009; Schneider et al., 2013). Iron accumulation and the presence of axonal spheroids in the brain are pathologic hallmarks of NBIA. Parkinsonism, dystonia, intellectual disability, and cognitive decline are common symptoms of NBIA. NBIA can be genetically classified as follows: (1) NBIA1 caused by mutations in the pantothenate kinase 2 gene * Corresponding author at: Department of Neurology, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan. Tel.: þ81 3 3813 3111; fax: þ81 3 5800 0547. E-mail address: [email protected] (N. Hattori). 0197-4580/$ e see front matter Ó 2015 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.neurobiolaging.2015.01.020
(PANK2), known as Hallervorden-Spatz disease, pantothenate kinase-associated neurodegeneration (PKAN) or aceruloplasminemia; (2) NBIA2A and 2B involving PLA2G6, infantile neuroaxonal dystrophy (INAD) or PLA2G6-associated neurodegeneration; (3) NBIA3 involving FTL, neuroferritinopathy; (4) NBIA4 involving mitochondrial protein-associated neurodegeneration caused by C19orf12; (5) NBIA5 involving mutations in WDR45, known as beta-propeller protein-associated neurodegeneration (BPAN) or static encephalopathy of childhood with neurodegeneration in adulthood; and (6) NBIA6 involving COASY, COASY protein-associated neurodegeneration (Dusi et al., 2014; Gregory et al., 2009; Haack et al., 2012; Saitsu et al., 2013; Schneider et al., 2013). Recently, RAB39B (a gene encoding a member of the Rab family of proteins) has been reported as a
Table 1 Clinical overview of the 7 patients with WDR45 gene mutations
Age at examination (y) Gender Mutation
Family history Neurologic symptoms Symptoms in childhood Initial walking Febrile convulsion at infant Speech ability
Parkinsonism Age at onset of parkinsonism (y) Rigidity Tremor Postural abnormality Dystonia Increasing deep tendon reflex Appearances of pathologic reflex Progressive dementia during adulthood Psychiatric symptoms Epileptic seizure Levodopa responsive Levodopa-induced dyskinesia Rett-like features Sleep problems Ocular defects Radiological features MRI T2 hypointense substantia nigra and globus pallidus (high iron) T1 hyperintense ‘halo’ in midbrain Eye-of-the-tiger sign White matter involvement Cerebral atrophy Cerebellar atrophy SPECT; area of hypoperfusion MIBG myocardial scintigraphy washout Neurophysiological examination EEG
Case 2
Case 3
Case 4
Case 5
Case 6
Case 7
37 Female c.587_588delTA (p.I196SfsX26) in exon 8 None
36 Female c.414_419delGTTGA (p.E138_F139del) in exon 6 None
33 Female c.628T>C(p.S210P) in exon 8
35 Female c.400C>T(p.R134X) in exon 6
41 Female c.293T>C(p.L98P) in exon 5
None
None
33 Female c.587_588delTA (p.I196SfsX26) in exon 8 None
Frequencies, %
None
100 (7/7)
3y þ No word
17 mo þ No word
18 mo þ A few words
2y þ No word
? þ No word
15 mo No word
20.6 8.29 85.7 (6/7) 100 (7/7)
þ
þ
þ
þ
þ
þ
14 mo þ Dysarthria and small voice þ
þ
þ
þ
þ
þ
þ
þ
100 (7/7)
Wheelchair Cognitive dysfunction þ 29 þ þ þ þ þ þ
Wheelchair Cognitive dysfunction þ 30 þ þ þ þ þ
Gait possible Cognitive dysfunction þ 32 þ þ þ þ
Wheelchair Cognitive dysfunction þ 32 þ þ þ þ
Wheelchair Cognitive dysfunction þ 34 þ þ þ þ þ
Gait possible Cognitive dysfunction þ 28 þ þ þ þ þ þ
Gait possible Cognitive dysfunction þ 39 þ þ þ þ
100 32.0 100 28.6 71.4 42.9 57.1 85.7 100
(7/7) 3.70 (7/7) (2/7) (5/7) (3/7) (4/7) (6/7) (7/7)
þ good þ
þ good þ þ þ
þ good þ
þ excellent
good
excellent þ þ
excellent
0 57.1 100 57.1 0 28.6 14.3
(0/7) (4/7) (7/7) (4/7) (0/7) (2/7) (1/7)
Cannot
þ
þ
þ
þ
þ
þ
100 (6/6)
Cannot Cannot Cannot Cannot Cannot NA NA
þ Diffuse NA NA
þ Temporal (lt > rt) lt frontotemporal
þ Diffuse (rt < lt) NA NA
þ Diffuse NA NA
þ Hemisphere (rt > lt) þ rt hemisphere
þ occipital
100 0 0 83.3 16.7
NA
abnormal
abnormal
normal
NA
abnormal
normal
100 (7/7)
100 (7/7)
K. Nishioka et al. / Neurobiology of Aging 36 (2015) 2004.e9e2004.e15
Cognitive dysfunction during childhood Developmental delay with intellectual disability Symptoms in adulthood Current status Initial symptom
Case 1 30 Female c.969_970insT (p.V324CfsX18) in exon 10 None
(6/6) (0/6) (0/6) (5/6) (1/6)
60 (3/5)
Key: EEG, electroencephalogram; lt, left; MIBG, [123I] meta-iodobenzylguanidine; MRI, magnetic resonance imaging; NA; not assessed; rt, right; SPECT, single-photon emission computed tomography. 2004.e10
0 NA 0 NA 0 NA 0 NA 1 (p.R635X single hetero) NA 0 NA 5.0 2.8 (range 3e9) 0.25 0.50 (range 0e1) 4.8 2.9 (range 3e9) 0 32.8 12.0 (range 5e83) 22.0 7.6 (range 2.5e30) 10.4 11.9 (range 0e72) 0 4 (3:1) 98 (48:48)
2.1. Participants
Key: AAO, age at onset; INAD, infantile neuroaxonal dystrophy; NA, not assessed.
0 0 0 0
PANK2 PLA2G6 WDR45
10.8 12.1 (range 1e43) 7 (25.00%) 0 33.0 9.6 (range 12e50) 23.8 11.2 (range 3e40)
1) Early-onset parkinsonism with intellectual disability (AAO C (p.S210P) in exon 8 is a novel missense
mutation, and the position of the amino acid is highly conserved in many species (Supplementary Fig. 1). None of the patients presented a positive family history of disease; thus, to assess whether the identified mutations are de novo, we screened all the available parents of mutation carriers. DNA was available for both parents of cases 1, 2, and 6 and the mother of cases 3 and 7; unfortunately, DNA was not available for parents of cases 4 and 5. This analysis failed to identify any of the WDR45 mutations in patients’ parents. cDNA sequencing indicates a selective expression of the mutant allele for cases 1 and 7 and expression of both alleles for the mutation identified in cases 2 and 6, indicating that the WDR45 gene has 2 types of transcription (Fig. 2). Clinical course showed that patients with WDR45 mutations had 2 phases in the progression of the disease: (1) intellectual disability and febrile seizures in childhood, and subsequently, (2) parkinsonism and advanced cognitive decline in adulthood after their 20s (Table 1). In 6 cases (except for case 3), there was noticeable progressive cognitive decline coinciding with the onset of
Fig. 2. The results of reverse transcriptase polymerase chain reaction indicate homozygous mutations of complementary DNA in cases 1 and 7 and heterozygous mutations in cases 2 and 6.
2004.e13
K. Nishioka et al. / Neurobiology of Aging 36 (2015) 2004.e9e2004.e15
Fig. 3. The axial-view brain magnetic resonance image indicates prominent features in patients with WDR45 mutations. (A) The halo in the substantia nigra in the axial T1weighted image (T1WI), (B) hypointense in the T2-weighted image (T2WI) in cerebral peduncles, and (C) marked atrophy in bilateral frontotemporal lobe in T1WI of case 2. (D) T1WI and (E) T2WI of case 3 are similar to findings on panels A and B. Images (F and G) of case 3 show hypointense signal in T1WI and T2WI in bilateral globus pallidus and disproportional atrophy in left temporal lobe. Images of case 4 (HeJ) demonstrate findings similar to those on panels A, B, and G, especially marked disproportional atrophy in left temporal lobe. The image of case 5 (K) indicates the diffuse atrophy in frontotemporal lobes in axial T1. Imaging findings (L) of case 5 are the same as those on panel B. Imaging findings of case 7 (MeO) are similar to those on panels A, B, and G. (P) Mid brain in T1WI, (Q) in T2WI, and (R) globus pallidus and basal ganglia in T1WI, (S) in T2WI of a 33-year-old female are shown as normal control.
parkinsonism. All cases had intellectual disability in childhood, commonly accompanied with high prevalence of febrile convulsion at infant stage (85.7%, 6 of 7). Five patients did not have verbal communication, and 2 patients had limited vocabulary. In adulthood, Mini-Mental State Examination could not be evaluated because of severe cognitive problems and language impairment. In terms of parkinsonism, akinesia, rigidity, and postural abnormality were prominent from the age of 32.0 3.70 years, but tremor and dystonia were lesser symptoms. Increased deep tendon reflexes were seen in half of patients (57.1%, 4 of 7), and pathologic reflexes such as Babinski sign appeared at a higher prevalence (85.7%, 6 of 7). None of the patients had complications of psychiatric symptoms.
A good response to levodopa was seen in all patients (100%, 7 of 7). Three patients in particular (cases 4, 6, and 7) showed excellent response to medication: case 4 showed marked improvement of gait after taking levodopa (300 mg), cabergoline (3 mg), and pramipexole (1.5 mg/d); in case 6, rigidity in all limbs was improved by levodopa (300 mg), ropinirole (0.75 mg), and trihexyphenidyl (4 mg/d); and in case 7, gait ability and akinesia were improved by levodopa (200 mg/d). Four patients developed levodopa-induced dyskinesia (57.1%, 4 of 7). Four patients had history of epileptic discharges (57.1%, 4 of 7). Electroencephalogram abnormalities were detected among 3 patients (60%, 3 of 5). Rett-like hand stereotypies, sleep problems, and ocular defects were not prominent.
K. Nishioka et al. / Neurobiology of Aging 36 (2015) 2004.e9e2004.e15
2004.e14
Table 3 Summary of clinical data combined with the previous reports and our cases Author
Number of patients
Female
Male
Family history, (%)
Mental retardation, (%)
Progressive cognitive dysfunction in adulthood, (%)
Dystonia, (%)
Dopa response, (%)
Parkinsonism, (%)
MRI findings T2 hypointense in Gp and SN, (%)
Haack et al. (2) Saitsu et al. (3) Hayflick et al. (5) Verhoeven et al. (6) Rathore et al. (7) Ichinose et al. (8) Ours Total
14 5 23 3 1 1 7 54
13 5 20 3 1 1 7 50
1 0 3 0 0 0 0 4
0 (0/14) 0 (0/5) 0 (0/23) 0 (0/3) NA NA 0 (7/7) 0 (0/52)
NA 100 100 100 100 100 100 100
NA 100 100 100 100 100 100 100
NA 100 100 100 100 100 42.9 90.0
NA NA 100 50 0 100 85.7 86.4
NA 100 91.3 66.7 0 100 100 90.0
NA 100 100 100 100 100 100 100
(5/5) (23/23) (3/3) (1/1) (1/1) (7/7) (40/40)
(5/5) (23/23) (3/3) (1/1) (1/1) (7/7) (40/40)
(5/5) (23/23) (3/3) (1/1) (1/1) (3/7) (36/40)
(11/11) (1/2) (0/1) (1/1) (6/7) (19/22)
(5/5) (21/23) (2/3) (0/1) (1/1) (7/7) (36/40)
(5/5) (22/22) (2/2) (1/1) (1/1) (6/6) (37/37)
Key: MRI, magnetic resonance imaging; NA; not assessed.
Brain magnetic resonance imaging (MRI) indicated characteristic features such as high intensity in T1-weighted images; halo, and low-intensity changes in T2-weighted images in the substantia nigra, the globus pallidus, and cerebral peduncles in all examined cases. Cases 2, 3, 4, 5, and 6 showed diffuse atrophy of the cerebrum (Fig. 3). Cases 3, 4, and 6 demonstrated disproportionate hemisphere atrophy. Only case 6 had cerebellar atrophy. Brain MRI assessment of all 6 cases showed no evidence of eye-of-the-tiger sign and white matter involvement. The single-photon emission computed tomography of 3 cases (3, 6, and 7) indicated nonspecific hypoperfusion: bilateral frontal and left temporal lobe regions in case 3; right frontal, temporal, occipital, and parietal lobe in case 6; and bilateral occipital lobe in case 7. 4. Discussion We found 7 patients with heterozygous WDR45 mutations, 5 of whom had not been previously described. In our cohort, the prevalence of the WDR45 mutations was higher among NBIA patients (18.4%) compared with other genes implicated in NBIA, and the mutations were only found in the specific cohort of intellectual disability and young-onset parkinsonism. To our knowledge, there are no reports of a comprehensive cross-sectional study of a single cohort presenting the same symptoms for mutations in NBIA genes. The precise prevalence of mutations in each gene still remains unknown. However, previous data indicate that the prevalence of mutations in NBIA is 35%e50% for PANK2, 20% for PLA2G6, and 6%e 10% for C19orf12 (Hartig et al., 2011; Hayflick et al., 2013; Hogarth et al., 2013). The distribution observed in our population is quite distinct, and this is likely owing to either our focus on patients with intellectual disability in childhood and young-onset parkinsonism (40 years) or ethnically specific differences between studied populations. In addition, our sample size is small (n ¼ 32), and further studies are needed to accurately evaluate the prevalence of mutations in these genes. All patients with WDR45 mutations had 2 phases of disease course, similar to that reported previously (Haack et al., 2012; Hayflick et al., 2013; Ichinose et al., 2014; Rathore et al., 2014; Saitsu et al., 2013; Verhoeven et al., 2014). We reviewed all available clinical data of patients with BPAN from previous reports and our present study (Table 3). Interestingly, all 40 patients with BPAN present common clinical features such as high prevalence of intellectual disability (100%; 40 of 40), progressive cognitive dysfunction in adulthood (100%; 40 of 40), dystonia (90.0%; 36 of 40), good response to levodopa (86.0%; 19 of 22), parkinsonism (90.0%; 36/40), and T1-weighted image; halo, and low-intensity changes in T2-weighted images in the substantia nigra, the globus pallidus, and cerebral peduncles of brain MRI (100%; 37 of 37). Interestingly, most of the WDR45 mutation carriers described in our study and others (Haack et al., 2012) are female
(female:male ¼ 49:4), but the clinical features observed in males appear to be similar to those of females (Hayflick et al., 2013). Because the clinical features of BPAN are specific and distinct from other types of NBIA such as PKAN, INAD, neuroferritinopathy, mitochondrial protein-associated neurodegeneration, and COASY protein-associated neurodegeneration, it may be used to specifically establish a diagnosis. For example, BPAN does not involve optic nerve atrophy, severe psychosis, depressive state, choreoathetosis, spasticity, and is unresponsive to levodopa (Gregory et al., 2009). PKAN has some common features such as oculomotor abnormalities, pyramidal sign, or the eye-of-the-tiger sign on brain MRI, features that are less common in BPAN. Brain MRI of PKAN and BPAN shares some common features such as iron accumulation of globus pallidus, subthalamus, and nigra (Schneider et al., 2013). The second type of NBIA is PLA2G6-associated neurodegeneration, which is commonly characterized as dystoniaparkinsonism combined with pyramidal signs, eye movement abnormalities, cognitive declines, and psychiatric features. With the exception of cognitive decline, these symptoms are less prevalent in BPAN. In addition, neuroimaging of PLA2G6-associated neurodegeneration patients indicates that iron accumulation is not a major feature. Mitochondrial protein-associated neurodegeneration has the symptoms of spastic paraparesis, neuropathy, optic atrophy, and psychiatric symptoms, which are not generally seen in BPAN. All of the identified mutations in WDR45 were located within exons 5e10, and RT-PCR showed a heterozygous mutation in cDNA in 2 patients, supporting a previous case report (Saitsu et al., 2013). Some of the cases with BPAN showed biallelic expression, even on the X chromosome, and thus did not obey X-inactivation. In female mammals, about 15% of X-linked genes escape inactivation (Carrel and Willard, 2005). Thus, among our female patients, the coexistence of wild-type and mutant alleles was admitted in WDR45 cDNA. WDR45 encodes WIPI4, a 7-bladed beta-propeller protein involved in autophagy and part of the group of WD40 repeat proteins which are involved in cell cycle control, apoptosis, and autophagy (Behrends et al., 2010). WIPI4 regulates distribution of Atg9A-marked vesicles to autophagosomes that complete the autophagosome maturation (Itakura et al., 2012; Orsi et al., 2012). Mutations in WDR45 may result in impaired autophagy and lead to the accumulation of abnormal proteins. WDR45 may be involved in mechanisms that result in accumulation of iron in the brain and subsequently disturb brain development. One of the fascinating features of NBIA cases is iron accumulation in the globus pallidus, the substantia nigra, or cerebral peduncles. It was reported that iron homeostasis, mitochondrial ferritin, and neurologic disorders have strong association via the molecular pathways of transferrin, ferritin, mitoferrin, and ceruloplasmin (Schneider et al., 2013). The dysregulation of mitochondrial iron and ferritin especially in the outer cellular membrane has been
2004.e15
K. Nishioka et al. / Neurobiology of Aging 36 (2015) 2004.e9e2004.e15
reported to result in excess production of reactive oxygen species (Eaton and Qian, 2002). Oxidative stress causes neuronal death and denatured mitochondria in the substantia nigra, not only in the hereditary form of PD but also sporadic PD cases (Henchcliffe and Beal, 2008; Jenner, 2003). WDR45 mutations may relate to iron metabolism, mitochondrial denaturation, destruction of membranes, or emergence of dystrophic axonal spheroids, directly or indirectly, via the common pathway of NBIA and PD. 5. Conclusions We found 7 patients diagnosed with BPAN harboring WDR45 mutations, suggesting WDR45 as the most prevalent cause of BPAN in our Japanese population. These patients share common clinical phenotypes with prominent features similar to those seen in previous cases. Importantly, levodopa presents good response for motor symptoms. These results contribute to further understanding of BPAN and NBIA types and can help in the diagnosis of BPAN. Disclosure statement The authors report no disclosures relevant to the article. Acknowledgements The authors obtained insightful comments from Dr. Carles Vilariño-Güell at the University of British Columbia, Vancouver, Canada. Dr. Nishioka was supported by JSPS KAKNEHI grant number 2586076. The authors are grateful for the Grant-in-Aid for Scientific Research on Innovative Areas (25129707 to Drs. Funayama, 25111007 to Saiki, and 23111003 to Hattori), the Grant-in-Aid for Young Scientists (25860725 to Drs. Li, and 23689046 to Saiki), the Grant-in-Aid for Challenging Exploratory Research (24659435 to Dr. Saiki), Grant-in-Aid for Scientific Research (25461291 to Drs. Funayama and 24390224 to Hattori) from Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research on Priority Areas (Drs. Saiki and Hattori) from the Japanese Ministry of Education, Culture, Sports, Science and Technology, and the Grantsin-Aid from the Research Committee of CNS Degenerative Diseases (H26-Nanchitou-Nan-Ippan-085 to Dr. Hattori), the Grant-in-Aid for Health Labour Sciences Research Grant (H26-Nanchitou-NanIppan-085 to Dr. Hattori) from Ministry of Health, Labour and Welfare, and grants from the Life Science Foundation, the Takeda Scientific Foundation, the Cell Science Research Foundation, and the Nakajima Foundation (Dr. Saiki). Appendix A. Supplementary Data Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.neurobiolaging. 2015.01.020. References Behrends, C., Sowa, M.E., Gygi, S.P., Harper, J.W., 2010. Network organization of the human autophagy system. Nature 466, 68e76. Carrel, L., Willard, H.F., 2005. X-inactivation profile reveals extensive variability in Xlinked gene expression in females. Nature 434, 400e404. Dusi, S., Valletta, L., Haack, T.B., Tsuchiya, Y., Venco, P., Pasqualato, S., Goffrini, P., Tigano, M., Demchenko, N., Wieland, T., Schwarzmayr, T., Strom, T.M., Invernizzi, F., Garavaglia, B., Gregory, A., Sanford, L., Hamada, J., Bettencourt, C., Houlden, H., Chiapparini, L., Zorzi, G., Kurian, M.A., Nardocci, N., Prokisch, H., Hayflick, S., Gout, I., Tiranti, V., 2014. Exome sequence reveals mutations in CoA synthase as a cause of neurodegeneration with brain iron accumulation. Am. J. Hum. Genet. 94, 11e22.
Eaton, J.W., Qian, M., 2002. Molecular bases of cellular iron toxicity. Free Radic. Biol. Med. 32, 833e840. Gregory, A., Polster, B.J., Hayflick, S.J., 2009. Clinical and genetic delineation of neurodegeneration with brain iron accumulation. J. Med. Genet. 46, 73e80. Haack, T.B., Hogarth, P., Kruer, M.C., Gregory, A., Wieland, T., Schwarzmayr, T., Graf, E., Sanford, L., Meyer, E., Kara, E., Cuno, S.M., Harik, S.I., Dandu, V.H., Nardocci, N., Zorzi, G., Dunaway, T., Tarnopolsky, M., Skinner, S., Frucht, S., Hanspal, E., Schrander-Stumpel, C., Heron, D., Mignot, C., Garavaglia, B., Bhatia, K., Hardy, J., Strom, T.M., Boddaert, N., Houlden, H.H., Kurian, M.A., Meitinger, T., Prokisch, H., Hayflick, S.J., 2012. Exome sequencing reveals de novo WDR45 mutations causing a phenotypically distinct, X-linked dominant form of NBIA. Am. J. Hum. Genet. 91, 1144e1149. Hartig, M.B., Iuso, A., Haack, T., Kmiec, T., Jurkiewicz, E., Heim, K., Roeber, S., Tarabin, V., Dusi, S., Krajewska-Walasek, M., Jozwiak, S., Hempel, M., Winkelmann, J., Elstner, M., Oexle, K., Klopstock, T., Mueller-Felber, W., Gasser, T., Trenkwalder, C., Tiranti, V., Kretzschmar, H., Schmitz, G., Strom, T.M., Meitinger, T., Prokisch, H., 2011. Absence of an orphan mitochondrial protein, c19orf12, causes a distinct clinical subtype of neurodegeneration with brain iron accumulation. Am. J. Hum. Genet. 89, 543e550. Hayflick, S.J., Kruer, M.C., Gregory, A., Haack, T.B., Kurian, M.A., Houlden, H.H., Anderson, J., Boddaert, N., Sanford, L., Harik, S.I., Dandu, V.H., Nardocci, N., Zorzi, G., Dunaway, T., Tarnopolsky, M., Skinner, S., Holden, K.R., Frucht, S., Hanspal, E., Schrander-Stumpel, C., Mignot, C., Heron, D., Saunders, D.E., Kaminska, M., Lin, J.P., Lascelles, K., Cuno, S.M., Meyer, E., Garavaglia, B., Bhatia, K., de Silva, R., Crisp, S., Lunt, P., Carey, M., Hardy, J., Meitinger, T., Prokisch, H., Hogarth, P., 2013. b-Propeller protein-associated neurodegeneration: a new X-linked dominant disorder with brain iron accumulation. Brain 136 (Pt 6), 1708e1717. Henchcliffe, C., Beal, M.F., 2008. Mitochondrial biology and oxidative stress in Parkinson disease pathogenesis. Nat. Clin. Pract. Neurol. 4, 600e609. Hogarth, P., Gregory, A., Kruer, M.C., Sanford, L., Wagoner, W., Natowicz, M.R., Egel, R.T., Subramony, S.H., Goldman, J.G., Berry-Kravis, E., Foulds, N.C., Hammans, S.R., Desguerre, I., Rodriguez, D., Wilson, C., Diedrich, A., Green, S., Tran, H., Reese, L., Woltjer, R.L., Hayflick, S.J., 2013. New NBIA subtype: genetic, clinical, pathologic, and radiographic features of MPAN. Neurology 80, 268e275. Ichinose, Y., Miwa, M., Onohara, A., Obi, K., Shindo, K., Saitsu, H., Matsumoto, N., Takiyama, Y., 2014. Characteristic MRI findings in beta-propeller protein-associated neurodegeneration (BPAN). Neurol. Clin. Pract. 4, 175e177. Itakura, E., Kishi-Itakura, C., Koyama-Honda, I., Mizushima, N., 2012. Structures containing Atg9A and the ULK1 complex independently target depolarized mitochondria at initial stages of Parkin-mediated mitophagy. J. Cell Sci. 125 (Pt 6), 1488e1499. Jenner, P., 2003. Oxidative stress in Parkinson’s disease. Ann. Neurol. 53 (Suppl 3), S26eS36 discussion S-8. Orsi, A., Razi, M., Dooley, H.C., Robinson, D., Weston, A.E., Collinson, L.M., Tooze, S.A., 2012. Dynamic and transient interactions of Atg9 with autophagosomes, but not membrane integration, are required for autophagy. Mol. Biol. Cell 23, 1860e1873. Paisan-Ruiz, C., Bhatia, K.P., Li, A., Hernandez, D., Davis, M., Wood, N.W., Hardy, J., Houlden, H., Singleton, A., Schneider, S.A., 2009. Characterization of PLA2G6 as a locus for dystonia-parkinsonism. Ann. Neurol. 65, 19e23. Rathore, G.S., Schaaf, C.P., Stocco, A.J., 2014. Novel mutation of the WDR45 gene causing beta-propeller protein-associated neurodegeneration. Mov. Disord. 29, 574e575. Saitsu, H., Nishimura, T., Muramatsu, K., Kodera, H., Kumada, S., Sugai, K., KasaiYoshida, E., Sawaura, N., Nishida, H., Hoshino, A., Ryujin, F., Yoshioka, S., Nishiyama, K., Kondo, Y., Tsurusaki, Y., Nakashima, M., Miyake, N., Arakawa, H., Kato, M., Mizushima, N., Matsumoto, N., 2013. De novo mutations in the autophagy gene WDR45 cause static encephalopathy of childhood with neurodegeneration in adulthood. Nat. Genet. 45, 445e449, 9e1. Schneider, S.A., Dusek, P., Hardy, J., Westenberger, A., Jankovic, J., Bhatia, K.P., 2013. Genetics and pathophysiology of neurodegeneration with brain iron accumulation (NBIA). Curr. Neuropharmacol. 11, 59e79. Stirnimann, C.U., Petsalaki, E., Russell, R.B., Muller, C.W., 2010. WD40 proteins propel cellular networks. Trends Biochem. Sci. 35, 565e574. Verhoeven, W.M., Egger, J.I., Koolen, D.A., Yntema, H., Olgiati, S., Breedveld, G.J., Bonifati, V., van de Warrenburg, B.P., 2014. Beta-propeller protein-associated neurodegeneration (BPAN), a rare form of NBIA: novel mutations and neuropsychiatric phenotype in three adult patients. Parkinsonism Relat. Disord. 20, 332e336. Wilson, G.R., Sim, J.C., McLean, C., Giannandrea, M., Galea, C.A., Riseley, J.R., Stephenson, S.E., Fitzpatrick, E., Haas, S.A., Pope, K., Hogan, K.J., Gregg, R.G., Bromhead, C.J., Wargowski, D.S., Lawrence, C.H., James, P.A., Churchyard, A., Gao, Y., Phelan, D.G., Gillies, G., Salce, N., Stanford, L., Marsh, A.P., Mignogna, M.L., Hayflick, S.J., Leventer, R.J., Delatycki, M.B., Mellick, G.D., Kalscheuer, V.M., D’Adamo, P., Bahlo, M., Amor, D.J., Lockhart, P.J., 2014. Mutations in RAB39B cause X-linked intellectual disability and early-onset Parkinson disease with alpha-synuclein pathology. Am. J. Hum. Genet. 95, 729e735.
Contents lists available at ScienceDirect
Neurobiology of Aging journal homepage: www.elsevier.com/locate/neuaging
High frequency of beta-propeller protein-associated neurodegeneration (BPAN) among patients with intellectual disability and young-onset parkinsonism Kenya Nishioka a, Genko Oyama a, Hiroyo Yoshino b, Yuanzhe Li a, Takashi Matsushima a, Chisen Takeuchi c, Yoko Mochizuki c, Madoka Mori-Yoshimura d, Miho Murata d, Chikara Yamasita e, Norimichi Nakamura e, Yohei Konishi f, Kazuki Ohi g, Keiji Ichikawa g, Tatsuhiro Terada h, Tomokazu Obi h, Manabu Funayama a, b, Shinji Saiki a, Nobutaka Hattori a, b, * a
Department of Neurology, Juntendo University School of Medicine, Tokyo, Japan Research Institute for Diseases of Old Age, Graduate School of Medicine, Juntendo University, Tokyo, Japan Department of Neurology, Tokyo Metropolitan Kita Medical and Rehabilitation Center for the Disabled, Tokyo, Japan d Department of Neurology, National Centre Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan e Department of Neurology, Kyushu University Hospital, Fukuoka, Japan f Department of Neurology, Yotsukaidou Tokushukai Medical Center, Chiba, Japan g Department of Neurology, Hyogo Prefectural Amagasaki Hospital, Hyogo, Japan h Department of Neurology, Shizuoka Institute of Epilepsy and Neurological Disorders, Shizuoka, Japan b c
a r t i c l e i n f o
a b s t r a c t
Article history: Received 6 November 2014 Received in revised form 22 January 2015 Accepted 24 January 2015 Available online 30 January 2015
Neurodegeneration with brain iron accumulation (NBIA) is a genetically heterogeneous disorder, characterized by the accumulation of iron in regions such as the basal ganglia. We enrolled 28 patients with childhood intellectual disability and young-onset parkinsonism (40 years at onset) and 4 patients with infantile neuroaxonal dystrophy. All had been clinically diagnosed, and the prevalence of genetic mutations linked to NBIA (PANK2 [exons 1e7], PLA2G6 [exons 2e17], C19orf12 [exons 1e3], WDR45 [exons 2e11], COASY [exons 1e9], FA2H [exons 1e7], and RAB39B [exons 1, 2]) was evaluated. We detected 7 female patients (25.0%, 7 of 28) with de novo heterozygote WDR45 mutations, which are known to be pathogenic for beta-propeller protein-associated neurodegeneration. All 7 patients had common clinical features. Pathogenic mutations in other NBIA genes were not found. We also screened 98 patients with early-onset parkinsonism without intellectual disability and 110 normal controls of Japanese origin for WDR45 mutations. None had WDR45 mutations. Our data suggest a high frequency of beta-propeller protein-associated neurodegeneration mutations in the Japanese population. Ó 2015 Elsevier Inc. All rights reserved.
Keywords: Neurodegeneration with brain iron accumulation Beta-propeller protein-associated neurodegeneration Parkinsonism Intellectual disability WDR45
1. Introduction Neurodegeneration with brain iron accumulation (NBIA) is clinically characterized by brain iron accumulation in the basal ganglia and other brain regions (Gregory et al., 2009; Schneider et al., 2013). Iron accumulation and the presence of axonal spheroids in the brain are pathologic hallmarks of NBIA. Parkinsonism, dystonia, intellectual disability, and cognitive decline are common symptoms of NBIA. NBIA can be genetically classified as follows: (1) NBIA1 caused by mutations in the pantothenate kinase 2 gene * Corresponding author at: Department of Neurology, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan. Tel.: þ81 3 3813 3111; fax: þ81 3 5800 0547. E-mail address: [email protected] (N. Hattori). 0197-4580/$ e see front matter Ó 2015 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.neurobiolaging.2015.01.020
(PANK2), known as Hallervorden-Spatz disease, pantothenate kinase-associated neurodegeneration (PKAN) or aceruloplasminemia; (2) NBIA2A and 2B involving PLA2G6, infantile neuroaxonal dystrophy (INAD) or PLA2G6-associated neurodegeneration; (3) NBIA3 involving FTL, neuroferritinopathy; (4) NBIA4 involving mitochondrial protein-associated neurodegeneration caused by C19orf12; (5) NBIA5 involving mutations in WDR45, known as beta-propeller protein-associated neurodegeneration (BPAN) or static encephalopathy of childhood with neurodegeneration in adulthood; and (6) NBIA6 involving COASY, COASY protein-associated neurodegeneration (Dusi et al., 2014; Gregory et al., 2009; Haack et al., 2012; Saitsu et al., 2013; Schneider et al., 2013). Recently, RAB39B (a gene encoding a member of the Rab family of proteins) has been reported as a
Table 1 Clinical overview of the 7 patients with WDR45 gene mutations
Age at examination (y) Gender Mutation
Family history Neurologic symptoms Symptoms in childhood Initial walking Febrile convulsion at infant Speech ability
Parkinsonism Age at onset of parkinsonism (y) Rigidity Tremor Postural abnormality Dystonia Increasing deep tendon reflex Appearances of pathologic reflex Progressive dementia during adulthood Psychiatric symptoms Epileptic seizure Levodopa responsive Levodopa-induced dyskinesia Rett-like features Sleep problems Ocular defects Radiological features MRI T2 hypointense substantia nigra and globus pallidus (high iron) T1 hyperintense ‘halo’ in midbrain Eye-of-the-tiger sign White matter involvement Cerebral atrophy Cerebellar atrophy SPECT; area of hypoperfusion MIBG myocardial scintigraphy washout Neurophysiological examination EEG
Case 2
Case 3
Case 4
Case 5
Case 6
Case 7
37 Female c.587_588delTA (p.I196SfsX26) in exon 8 None
36 Female c.414_419delGTTGA (p.E138_F139del) in exon 6 None
33 Female c.628T>C(p.S210P) in exon 8
35 Female c.400C>T(p.R134X) in exon 6
41 Female c.293T>C(p.L98P) in exon 5
None
None
33 Female c.587_588delTA (p.I196SfsX26) in exon 8 None
Frequencies, %
None
100 (7/7)
3y þ No word
17 mo þ No word
18 mo þ A few words
2y þ No word
? þ No word
15 mo No word
20.6 8.29 85.7 (6/7) 100 (7/7)
þ
þ
þ
þ
þ
þ
14 mo þ Dysarthria and small voice þ
þ
þ
þ
þ
þ
þ
þ
100 (7/7)
Wheelchair Cognitive dysfunction þ 29 þ þ þ þ þ þ
Wheelchair Cognitive dysfunction þ 30 þ þ þ þ þ
Gait possible Cognitive dysfunction þ 32 þ þ þ þ
Wheelchair Cognitive dysfunction þ 32 þ þ þ þ
Wheelchair Cognitive dysfunction þ 34 þ þ þ þ þ
Gait possible Cognitive dysfunction þ 28 þ þ þ þ þ þ
Gait possible Cognitive dysfunction þ 39 þ þ þ þ
100 32.0 100 28.6 71.4 42.9 57.1 85.7 100
(7/7) 3.70 (7/7) (2/7) (5/7) (3/7) (4/7) (6/7) (7/7)
þ good þ
þ good þ þ þ
þ good þ
þ excellent
good
excellent þ þ
excellent
0 57.1 100 57.1 0 28.6 14.3
(0/7) (4/7) (7/7) (4/7) (0/7) (2/7) (1/7)
Cannot
þ
þ
þ
þ
þ
þ
100 (6/6)
Cannot Cannot Cannot Cannot Cannot NA NA
þ Diffuse NA NA
þ Temporal (lt > rt) lt frontotemporal
þ Diffuse (rt < lt) NA NA
þ Diffuse NA NA
þ Hemisphere (rt > lt) þ rt hemisphere
þ occipital
100 0 0 83.3 16.7
NA
abnormal
abnormal
normal
NA
abnormal
normal
100 (7/7)
100 (7/7)
K. Nishioka et al. / Neurobiology of Aging 36 (2015) 2004.e9e2004.e15
Cognitive dysfunction during childhood Developmental delay with intellectual disability Symptoms in adulthood Current status Initial symptom
Case 1 30 Female c.969_970insT (p.V324CfsX18) in exon 10 None
(6/6) (0/6) (0/6) (5/6) (1/6)
60 (3/5)
Key: EEG, electroencephalogram; lt, left; MIBG, [123I] meta-iodobenzylguanidine; MRI, magnetic resonance imaging; NA; not assessed; rt, right; SPECT, single-photon emission computed tomography. 2004.e10
0 NA 0 NA 0 NA 0 NA 1 (p.R635X single hetero) NA 0 NA 5.0 2.8 (range 3e9) 0.25 0.50 (range 0e1) 4.8 2.9 (range 3e9) 0 32.8 12.0 (range 5e83) 22.0 7.6 (range 2.5e30) 10.4 11.9 (range 0e72) 0 4 (3:1) 98 (48:48)
2.1. Participants
Key: AAO, age at onset; INAD, infantile neuroaxonal dystrophy; NA, not assessed.
0 0 0 0
PANK2 PLA2G6 WDR45
10.8 12.1 (range 1e43) 7 (25.00%) 0 33.0 9.6 (range 12e50) 23.8 11.2 (range 3e40)
1) Early-onset parkinsonism with intellectual disability (AAO C (p.S210P) in exon 8 is a novel missense
mutation, and the position of the amino acid is highly conserved in many species (Supplementary Fig. 1). None of the patients presented a positive family history of disease; thus, to assess whether the identified mutations are de novo, we screened all the available parents of mutation carriers. DNA was available for both parents of cases 1, 2, and 6 and the mother of cases 3 and 7; unfortunately, DNA was not available for parents of cases 4 and 5. This analysis failed to identify any of the WDR45 mutations in patients’ parents. cDNA sequencing indicates a selective expression of the mutant allele for cases 1 and 7 and expression of both alleles for the mutation identified in cases 2 and 6, indicating that the WDR45 gene has 2 types of transcription (Fig. 2). Clinical course showed that patients with WDR45 mutations had 2 phases in the progression of the disease: (1) intellectual disability and febrile seizures in childhood, and subsequently, (2) parkinsonism and advanced cognitive decline in adulthood after their 20s (Table 1). In 6 cases (except for case 3), there was noticeable progressive cognitive decline coinciding with the onset of
Fig. 2. The results of reverse transcriptase polymerase chain reaction indicate homozygous mutations of complementary DNA in cases 1 and 7 and heterozygous mutations in cases 2 and 6.
2004.e13
K. Nishioka et al. / Neurobiology of Aging 36 (2015) 2004.e9e2004.e15
Fig. 3. The axial-view brain magnetic resonance image indicates prominent features in patients with WDR45 mutations. (A) The halo in the substantia nigra in the axial T1weighted image (T1WI), (B) hypointense in the T2-weighted image (T2WI) in cerebral peduncles, and (C) marked atrophy in bilateral frontotemporal lobe in T1WI of case 2. (D) T1WI and (E) T2WI of case 3 are similar to findings on panels A and B. Images (F and G) of case 3 show hypointense signal in T1WI and T2WI in bilateral globus pallidus and disproportional atrophy in left temporal lobe. Images of case 4 (HeJ) demonstrate findings similar to those on panels A, B, and G, especially marked disproportional atrophy in left temporal lobe. The image of case 5 (K) indicates the diffuse atrophy in frontotemporal lobes in axial T1. Imaging findings (L) of case 5 are the same as those on panel B. Imaging findings of case 7 (MeO) are similar to those on panels A, B, and G. (P) Mid brain in T1WI, (Q) in T2WI, and (R) globus pallidus and basal ganglia in T1WI, (S) in T2WI of a 33-year-old female are shown as normal control.
parkinsonism. All cases had intellectual disability in childhood, commonly accompanied with high prevalence of febrile convulsion at infant stage (85.7%, 6 of 7). Five patients did not have verbal communication, and 2 patients had limited vocabulary. In adulthood, Mini-Mental State Examination could not be evaluated because of severe cognitive problems and language impairment. In terms of parkinsonism, akinesia, rigidity, and postural abnormality were prominent from the age of 32.0 3.70 years, but tremor and dystonia were lesser symptoms. Increased deep tendon reflexes were seen in half of patients (57.1%, 4 of 7), and pathologic reflexes such as Babinski sign appeared at a higher prevalence (85.7%, 6 of 7). None of the patients had complications of psychiatric symptoms.
A good response to levodopa was seen in all patients (100%, 7 of 7). Three patients in particular (cases 4, 6, and 7) showed excellent response to medication: case 4 showed marked improvement of gait after taking levodopa (300 mg), cabergoline (3 mg), and pramipexole (1.5 mg/d); in case 6, rigidity in all limbs was improved by levodopa (300 mg), ropinirole (0.75 mg), and trihexyphenidyl (4 mg/d); and in case 7, gait ability and akinesia were improved by levodopa (200 mg/d). Four patients developed levodopa-induced dyskinesia (57.1%, 4 of 7). Four patients had history of epileptic discharges (57.1%, 4 of 7). Electroencephalogram abnormalities were detected among 3 patients (60%, 3 of 5). Rett-like hand stereotypies, sleep problems, and ocular defects were not prominent.
K. Nishioka et al. / Neurobiology of Aging 36 (2015) 2004.e9e2004.e15
2004.e14
Table 3 Summary of clinical data combined with the previous reports and our cases Author
Number of patients
Female
Male
Family history, (%)
Mental retardation, (%)
Progressive cognitive dysfunction in adulthood, (%)
Dystonia, (%)
Dopa response, (%)
Parkinsonism, (%)
MRI findings T2 hypointense in Gp and SN, (%)
Haack et al. (2) Saitsu et al. (3) Hayflick et al. (5) Verhoeven et al. (6) Rathore et al. (7) Ichinose et al. (8) Ours Total
14 5 23 3 1 1 7 54
13 5 20 3 1 1 7 50
1 0 3 0 0 0 0 4
0 (0/14) 0 (0/5) 0 (0/23) 0 (0/3) NA NA 0 (7/7) 0 (0/52)
NA 100 100 100 100 100 100 100
NA 100 100 100 100 100 100 100
NA 100 100 100 100 100 42.9 90.0
NA NA 100 50 0 100 85.7 86.4
NA 100 91.3 66.7 0 100 100 90.0
NA 100 100 100 100 100 100 100
(5/5) (23/23) (3/3) (1/1) (1/1) (7/7) (40/40)
(5/5) (23/23) (3/3) (1/1) (1/1) (7/7) (40/40)
(5/5) (23/23) (3/3) (1/1) (1/1) (3/7) (36/40)
(11/11) (1/2) (0/1) (1/1) (6/7) (19/22)
(5/5) (21/23) (2/3) (0/1) (1/1) (7/7) (36/40)
(5/5) (22/22) (2/2) (1/1) (1/1) (6/6) (37/37)
Key: MRI, magnetic resonance imaging; NA; not assessed.
Brain magnetic resonance imaging (MRI) indicated characteristic features such as high intensity in T1-weighted images; halo, and low-intensity changes in T2-weighted images in the substantia nigra, the globus pallidus, and cerebral peduncles in all examined cases. Cases 2, 3, 4, 5, and 6 showed diffuse atrophy of the cerebrum (Fig. 3). Cases 3, 4, and 6 demonstrated disproportionate hemisphere atrophy. Only case 6 had cerebellar atrophy. Brain MRI assessment of all 6 cases showed no evidence of eye-of-the-tiger sign and white matter involvement. The single-photon emission computed tomography of 3 cases (3, 6, and 7) indicated nonspecific hypoperfusion: bilateral frontal and left temporal lobe regions in case 3; right frontal, temporal, occipital, and parietal lobe in case 6; and bilateral occipital lobe in case 7. 4. Discussion We found 7 patients with heterozygous WDR45 mutations, 5 of whom had not been previously described. In our cohort, the prevalence of the WDR45 mutations was higher among NBIA patients (18.4%) compared with other genes implicated in NBIA, and the mutations were only found in the specific cohort of intellectual disability and young-onset parkinsonism. To our knowledge, there are no reports of a comprehensive cross-sectional study of a single cohort presenting the same symptoms for mutations in NBIA genes. The precise prevalence of mutations in each gene still remains unknown. However, previous data indicate that the prevalence of mutations in NBIA is 35%e50% for PANK2, 20% for PLA2G6, and 6%e 10% for C19orf12 (Hartig et al., 2011; Hayflick et al., 2013; Hogarth et al., 2013). The distribution observed in our population is quite distinct, and this is likely owing to either our focus on patients with intellectual disability in childhood and young-onset parkinsonism (40 years) or ethnically specific differences between studied populations. In addition, our sample size is small (n ¼ 32), and further studies are needed to accurately evaluate the prevalence of mutations in these genes. All patients with WDR45 mutations had 2 phases of disease course, similar to that reported previously (Haack et al., 2012; Hayflick et al., 2013; Ichinose et al., 2014; Rathore et al., 2014; Saitsu et al., 2013; Verhoeven et al., 2014). We reviewed all available clinical data of patients with BPAN from previous reports and our present study (Table 3). Interestingly, all 40 patients with BPAN present common clinical features such as high prevalence of intellectual disability (100%; 40 of 40), progressive cognitive dysfunction in adulthood (100%; 40 of 40), dystonia (90.0%; 36 of 40), good response to levodopa (86.0%; 19 of 22), parkinsonism (90.0%; 36/40), and T1-weighted image; halo, and low-intensity changes in T2-weighted images in the substantia nigra, the globus pallidus, and cerebral peduncles of brain MRI (100%; 37 of 37). Interestingly, most of the WDR45 mutation carriers described in our study and others (Haack et al., 2012) are female
(female:male ¼ 49:4), but the clinical features observed in males appear to be similar to those of females (Hayflick et al., 2013). Because the clinical features of BPAN are specific and distinct from other types of NBIA such as PKAN, INAD, neuroferritinopathy, mitochondrial protein-associated neurodegeneration, and COASY protein-associated neurodegeneration, it may be used to specifically establish a diagnosis. For example, BPAN does not involve optic nerve atrophy, severe psychosis, depressive state, choreoathetosis, spasticity, and is unresponsive to levodopa (Gregory et al., 2009). PKAN has some common features such as oculomotor abnormalities, pyramidal sign, or the eye-of-the-tiger sign on brain MRI, features that are less common in BPAN. Brain MRI of PKAN and BPAN shares some common features such as iron accumulation of globus pallidus, subthalamus, and nigra (Schneider et al., 2013). The second type of NBIA is PLA2G6-associated neurodegeneration, which is commonly characterized as dystoniaparkinsonism combined with pyramidal signs, eye movement abnormalities, cognitive declines, and psychiatric features. With the exception of cognitive decline, these symptoms are less prevalent in BPAN. In addition, neuroimaging of PLA2G6-associated neurodegeneration patients indicates that iron accumulation is not a major feature. Mitochondrial protein-associated neurodegeneration has the symptoms of spastic paraparesis, neuropathy, optic atrophy, and psychiatric symptoms, which are not generally seen in BPAN. All of the identified mutations in WDR45 were located within exons 5e10, and RT-PCR showed a heterozygous mutation in cDNA in 2 patients, supporting a previous case report (Saitsu et al., 2013). Some of the cases with BPAN showed biallelic expression, even on the X chromosome, and thus did not obey X-inactivation. In female mammals, about 15% of X-linked genes escape inactivation (Carrel and Willard, 2005). Thus, among our female patients, the coexistence of wild-type and mutant alleles was admitted in WDR45 cDNA. WDR45 encodes WIPI4, a 7-bladed beta-propeller protein involved in autophagy and part of the group of WD40 repeat proteins which are involved in cell cycle control, apoptosis, and autophagy (Behrends et al., 2010). WIPI4 regulates distribution of Atg9A-marked vesicles to autophagosomes that complete the autophagosome maturation (Itakura et al., 2012; Orsi et al., 2012). Mutations in WDR45 may result in impaired autophagy and lead to the accumulation of abnormal proteins. WDR45 may be involved in mechanisms that result in accumulation of iron in the brain and subsequently disturb brain development. One of the fascinating features of NBIA cases is iron accumulation in the globus pallidus, the substantia nigra, or cerebral peduncles. It was reported that iron homeostasis, mitochondrial ferritin, and neurologic disorders have strong association via the molecular pathways of transferrin, ferritin, mitoferrin, and ceruloplasmin (Schneider et al., 2013). The dysregulation of mitochondrial iron and ferritin especially in the outer cellular membrane has been
2004.e15
K. Nishioka et al. / Neurobiology of Aging 36 (2015) 2004.e9e2004.e15
reported to result in excess production of reactive oxygen species (Eaton and Qian, 2002). Oxidative stress causes neuronal death and denatured mitochondria in the substantia nigra, not only in the hereditary form of PD but also sporadic PD cases (Henchcliffe and Beal, 2008; Jenner, 2003). WDR45 mutations may relate to iron metabolism, mitochondrial denaturation, destruction of membranes, or emergence of dystrophic axonal spheroids, directly or indirectly, via the common pathway of NBIA and PD. 5. Conclusions We found 7 patients diagnosed with BPAN harboring WDR45 mutations, suggesting WDR45 as the most prevalent cause of BPAN in our Japanese population. These patients share common clinical phenotypes with prominent features similar to those seen in previous cases. Importantly, levodopa presents good response for motor symptoms. These results contribute to further understanding of BPAN and NBIA types and can help in the diagnosis of BPAN. Disclosure statement The authors report no disclosures relevant to the article. Acknowledgements The authors obtained insightful comments from Dr. Carles Vilariño-Güell at the University of British Columbia, Vancouver, Canada. Dr. Nishioka was supported by JSPS KAKNEHI grant number 2586076. The authors are grateful for the Grant-in-Aid for Scientific Research on Innovative Areas (25129707 to Drs. Funayama, 25111007 to Saiki, and 23111003 to Hattori), the Grant-in-Aid for Young Scientists (25860725 to Drs. Li, and 23689046 to Saiki), the Grant-in-Aid for Challenging Exploratory Research (24659435 to Dr. Saiki), Grant-in-Aid for Scientific Research (25461291 to Drs. Funayama and 24390224 to Hattori) from Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research on Priority Areas (Drs. Saiki and Hattori) from the Japanese Ministry of Education, Culture, Sports, Science and Technology, and the Grantsin-Aid from the Research Committee of CNS Degenerative Diseases (H26-Nanchitou-Nan-Ippan-085 to Dr. Hattori), the Grant-in-Aid for Health Labour Sciences Research Grant (H26-Nanchitou-NanIppan-085 to Dr. Hattori) from Ministry of Health, Labour and Welfare, and grants from the Life Science Foundation, the Takeda Scientific Foundation, the Cell Science Research Foundation, and the Nakajima Foundation (Dr. Saiki). Appendix A. Supplementary Data Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.neurobiolaging. 2015.01.020. References Behrends, C., Sowa, M.E., Gygi, S.P., Harper, J.W., 2010. Network organization of the human autophagy system. Nature 466, 68e76. Carrel, L., Willard, H.F., 2005. X-inactivation profile reveals extensive variability in Xlinked gene expression in females. Nature 434, 400e404. Dusi, S., Valletta, L., Haack, T.B., Tsuchiya, Y., Venco, P., Pasqualato, S., Goffrini, P., Tigano, M., Demchenko, N., Wieland, T., Schwarzmayr, T., Strom, T.M., Invernizzi, F., Garavaglia, B., Gregory, A., Sanford, L., Hamada, J., Bettencourt, C., Houlden, H., Chiapparini, L., Zorzi, G., Kurian, M.A., Nardocci, N., Prokisch, H., Hayflick, S., Gout, I., Tiranti, V., 2014. Exome sequence reveals mutations in CoA synthase as a cause of neurodegeneration with brain iron accumulation. Am. J. Hum. Genet. 94, 11e22.
Eaton, J.W., Qian, M., 2002. Molecular bases of cellular iron toxicity. Free Radic. Biol. Med. 32, 833e840. Gregory, A., Polster, B.J., Hayflick, S.J., 2009. Clinical and genetic delineation of neurodegeneration with brain iron accumulation. J. Med. Genet. 46, 73e80. Haack, T.B., Hogarth, P., Kruer, M.C., Gregory, A., Wieland, T., Schwarzmayr, T., Graf, E., Sanford, L., Meyer, E., Kara, E., Cuno, S.M., Harik, S.I., Dandu, V.H., Nardocci, N., Zorzi, G., Dunaway, T., Tarnopolsky, M., Skinner, S., Frucht, S., Hanspal, E., Schrander-Stumpel, C., Heron, D., Mignot, C., Garavaglia, B., Bhatia, K., Hardy, J., Strom, T.M., Boddaert, N., Houlden, H.H., Kurian, M.A., Meitinger, T., Prokisch, H., Hayflick, S.J., 2012. Exome sequencing reveals de novo WDR45 mutations causing a phenotypically distinct, X-linked dominant form of NBIA. Am. J. Hum. Genet. 91, 1144e1149. Hartig, M.B., Iuso, A., Haack, T., Kmiec, T., Jurkiewicz, E., Heim, K., Roeber, S., Tarabin, V., Dusi, S., Krajewska-Walasek, M., Jozwiak, S., Hempel, M., Winkelmann, J., Elstner, M., Oexle, K., Klopstock, T., Mueller-Felber, W., Gasser, T., Trenkwalder, C., Tiranti, V., Kretzschmar, H., Schmitz, G., Strom, T.M., Meitinger, T., Prokisch, H., 2011. Absence of an orphan mitochondrial protein, c19orf12, causes a distinct clinical subtype of neurodegeneration with brain iron accumulation. Am. J. Hum. Genet. 89, 543e550. Hayflick, S.J., Kruer, M.C., Gregory, A., Haack, T.B., Kurian, M.A., Houlden, H.H., Anderson, J., Boddaert, N., Sanford, L., Harik, S.I., Dandu, V.H., Nardocci, N., Zorzi, G., Dunaway, T., Tarnopolsky, M., Skinner, S., Holden, K.R., Frucht, S., Hanspal, E., Schrander-Stumpel, C., Mignot, C., Heron, D., Saunders, D.E., Kaminska, M., Lin, J.P., Lascelles, K., Cuno, S.M., Meyer, E., Garavaglia, B., Bhatia, K., de Silva, R., Crisp, S., Lunt, P., Carey, M., Hardy, J., Meitinger, T., Prokisch, H., Hogarth, P., 2013. b-Propeller protein-associated neurodegeneration: a new X-linked dominant disorder with brain iron accumulation. Brain 136 (Pt 6), 1708e1717. Henchcliffe, C., Beal, M.F., 2008. Mitochondrial biology and oxidative stress in Parkinson disease pathogenesis. Nat. Clin. Pract. Neurol. 4, 600e609. Hogarth, P., Gregory, A., Kruer, M.C., Sanford, L., Wagoner, W., Natowicz, M.R., Egel, R.T., Subramony, S.H., Goldman, J.G., Berry-Kravis, E., Foulds, N.C., Hammans, S.R., Desguerre, I., Rodriguez, D., Wilson, C., Diedrich, A., Green, S., Tran, H., Reese, L., Woltjer, R.L., Hayflick, S.J., 2013. New NBIA subtype: genetic, clinical, pathologic, and radiographic features of MPAN. Neurology 80, 268e275. Ichinose, Y., Miwa, M., Onohara, A., Obi, K., Shindo, K., Saitsu, H., Matsumoto, N., Takiyama, Y., 2014. Characteristic MRI findings in beta-propeller protein-associated neurodegeneration (BPAN). Neurol. Clin. Pract. 4, 175e177. Itakura, E., Kishi-Itakura, C., Koyama-Honda, I., Mizushima, N., 2012. Structures containing Atg9A and the ULK1 complex independently target depolarized mitochondria at initial stages of Parkin-mediated mitophagy. J. Cell Sci. 125 (Pt 6), 1488e1499. Jenner, P., 2003. Oxidative stress in Parkinson’s disease. Ann. Neurol. 53 (Suppl 3), S26eS36 discussion S-8. Orsi, A., Razi, M., Dooley, H.C., Robinson, D., Weston, A.E., Collinson, L.M., Tooze, S.A., 2012. Dynamic and transient interactions of Atg9 with autophagosomes, but not membrane integration, are required for autophagy. Mol. Biol. Cell 23, 1860e1873. Paisan-Ruiz, C., Bhatia, K.P., Li, A., Hernandez, D., Davis, M., Wood, N.W., Hardy, J., Houlden, H., Singleton, A., Schneider, S.A., 2009. Characterization of PLA2G6 as a locus for dystonia-parkinsonism. Ann. Neurol. 65, 19e23. Rathore, G.S., Schaaf, C.P., Stocco, A.J., 2014. Novel mutation of the WDR45 gene causing beta-propeller protein-associated neurodegeneration. Mov. Disord. 29, 574e575. Saitsu, H., Nishimura, T., Muramatsu, K., Kodera, H., Kumada, S., Sugai, K., KasaiYoshida, E., Sawaura, N., Nishida, H., Hoshino, A., Ryujin, F., Yoshioka, S., Nishiyama, K., Kondo, Y., Tsurusaki, Y., Nakashima, M., Miyake, N., Arakawa, H., Kato, M., Mizushima, N., Matsumoto, N., 2013. De novo mutations in the autophagy gene WDR45 cause static encephalopathy of childhood with neurodegeneration in adulthood. Nat. Genet. 45, 445e449, 9e1. Schneider, S.A., Dusek, P., Hardy, J., Westenberger, A., Jankovic, J., Bhatia, K.P., 2013. Genetics and pathophysiology of neurodegeneration with brain iron accumulation (NBIA). Curr. Neuropharmacol. 11, 59e79. Stirnimann, C.U., Petsalaki, E., Russell, R.B., Muller, C.W., 2010. WD40 proteins propel cellular networks. Trends Biochem. Sci. 35, 565e574. Verhoeven, W.M., Egger, J.I., Koolen, D.A., Yntema, H., Olgiati, S., Breedveld, G.J., Bonifati, V., van de Warrenburg, B.P., 2014. Beta-propeller protein-associated neurodegeneration (BPAN), a rare form of NBIA: novel mutations and neuropsychiatric phenotype in three adult patients. Parkinsonism Relat. Disord. 20, 332e336. Wilson, G.R., Sim, J.C., McLean, C., Giannandrea, M., Galea, C.A., Riseley, J.R., Stephenson, S.E., Fitzpatrick, E., Haas, S.A., Pope, K., Hogan, K.J., Gregg, R.G., Bromhead, C.J., Wargowski, D.S., Lawrence, C.H., James, P.A., Churchyard, A., Gao, Y., Phelan, D.G., Gillies, G., Salce, N., Stanford, L., Marsh, A.P., Mignogna, M.L., Hayflick, S.J., Leventer, R.J., Delatycki, M.B., Mellick, G.D., Kalscheuer, V.M., D’Adamo, P., Bahlo, M., Amor, D.J., Lockhart, P.J., 2014. Mutations in RAB39B cause X-linked intellectual disability and early-onset Parkinson disease with alpha-synuclein pathology. Am. J. Hum. Genet. 95, 729e735.
