J Neurol (2015) 262:418–424 DOI 10.1007/s00415-014-7588-0
An 11-year retrospective experience of antibodies against the voltage-gated potassium channel (VGKC) complex from a tertiary neurological centre S. Huda • S. H. Wong • P. Pettingill • D. O’Connell • A. Vincent • M. Steiger
Received: 26 August 2014 / Revised: 14 November 2014 / Accepted: 15 November 2014 / Published online: 27 November 2014 Ó Springer-Verlag Berlin Heidelberg 2014
Abstract Acquired diseases classically associated with VGKC-complex antibodies include peripheral nerve hyperexcitability (PNH), Morvan’s syndrome, limbic encephalitis (LE), and epilepsy. However, not all such patients have VGKC-complex antibodies and antibodies have been reported in patients without a defined immunemediated syndrome. To analyse the clinical relevance of positive VGKC-complex antibodies requested on the basis of initial clinical suspicion. We retrospectively analysed patients with positive VGKC-complex antibodies ([100 pM) referred to our institution between 2001 and 2011. 1,614 VGKC-complex assays were performed in 1,298 patients. Titres [100 pM were detected in 57/1,298 (4 %) patients. A classic VGKC-complex channelopathy (60 %) was associated with VGKC-complex antibody titres [400 pM (p = 0.0004). LGI1 or CASPR2 antibodies were only detected in classic VGKC-complex channelopathies (LE; n = 3/4 and PNH; n = 1/5). VGKC-complex antibody titres \400 pM were seen with PNH (n = 15/22; 68 %) but also a heterogeneous range of central and/or peripheral nervous system disorders. Electromyography was supportive of PNH in 65 % of cases and symptomatic treatment was beneficial in 46 % of
S. Huda D. O’Connell M. Steiger Department of Neurology, Walton Centre for Neurology and Neurosurgery, Lower Lane, Fazarkerley, Liverpool L9 7LJ, UK S. Huda (&) P. Pettingill A. Vincent Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Level 6 West Wing, Oxford OX3 9DU, UK e-mail: [email protected] S. H. Wong Department of Neuro-ophthalmology, Moorfields Eye Hospital, 162 City Road, London EC1V 2PD, UK
patients. Irrespective of titre, the rate of malignancy in patients with VGKC-complex antibodies was higher than the age-matched national incidence of malignancy (OR 19.9, 95 % CI 8.97–44.0 p\0.0001). Clinical phenotyping and antibody titres [400 pM can help determine VGKCcomplex antibody relevance. Antibody titres \400 pM are associated with PNH but also a more heterogeneous clinical spectrum. The antibody association in the latter is of doubtful clinical relevance. The rate of malignancy was significantly higher than the national incidence irrespective of titre. Keywords Voltage-gated potassium channel complex Antibody Limbic encephalitis Peripheral nerve hyperexcitability Autoimmunity
Introduction Voltage-gated potassium channels (VGKC) play an important role in the regulation of membrane excitability. Acquired diseases classically associated with VGKCcomplex antibodies include neuromyotonia/peripheral nerve hyperexcitability (PNH), Morvan’s syndrome, limbic encephalitis (LE), and epilepsy. These disorders are the autoimmune equivalent of the inherited potassium channelopathies, which include neuromyotonia, epilepsy, and episodic ataxia [1–3]. The antibodies are directed against proteins of the voltage-gated potassium channel complex (VGKC-complex) which include Leucine-rich Glioma inactivated 1 (LGI1), Contactin-associated protein-2 (CASPR2), and Contactin-2 [4, 5]. Whilst the recognition of these specific targets has clarified some of the phenotypic variation seen in the associated diseases, VGKC-complex antibodies have
J Neurol (2015) 262:418–424
VGKC-complex antibody titre [400 pM 17/57 (30 %) patients had VGKC-complex antibody titres [400 pM. The median age of presentation was 59 years (27–77) with a male to female preponderance of 3:1 (Table 1). Sixteen of 17 (94.1 %) patients presented with a classic VGKC-complex channelopathy (LE; n = 8, PNH; n = 6, LE/PNH; n = 1, and Morvan’s syndrome; n = 1). This was higher than the proportion of patients with a classic VGKC-complex channelopathy [18/40 (45 %)] with VGKC-complex antibody titres \400 pM (Table 1; Fig. 2; p \ 0.0004). Patients in the [400 pM group were
We retrospectively analysed all patients referred to our institution between 2001 and 2011 who had positive VGKC-complex antibodies (titres [100 pM) reported. VGKC-complex antibodies had been requested by neurologists on the basis of primary clinical presentation, sent to the Oxford Neuroimmunology group for testing by radioimmunoprecipitation assay and identified through a computerised laboratory database . Sera still available (n = 19) were subsequently tested by cell-based assays (CBA) for antibodies to the VGKC-complex proteins LGI1, CASPR2, and Contactin-2; these tests were not available at the time of initial sampling. CBAs were performed using human embryonic kidney cells transfected with cDNAs for the individual proteins . Data were extracted through review of written and computerised records and included clinical presentation, treatment response, malignancy, neurophysiology, cerebrospinal fluid (CSF), sodium levels, brain imaging, sleep and autonomic disturbance. To the extent possible, missing data were obtained from referring hospitals. Neuromyotonia/peripheral nerve hyperexcitability, Morvan’s syndrome, limbic encephalitis, and epilepsy were regarded as classic VGKC-complex channelopathies. Data were also analysed with a VGKC-complex antibody titre of 400 pM as a cutoff value. This has previously been suggested as titres below this value were found in an elderly control group [6, 8]. The study was approved by the local institutional clinical governance and audit board and performed in accordance with the Helsinki Declaration of 1975, as revised in 2000 and 2008. Statistical analysis was carried out using GraphPad Prism Version 6.0A. We compared demographic, clinical, and serological data using student’s t test, Kolmogorov– Smirnov test, or Fisher’s exact test. In the absence of normality, a non-parametric Mann–Whitney test was performed. Statistical significance was defined as a two-sided p value less than 0.05. Comparison of cancer incidence rates was performed using odds ratios in age-matched data from the United Kingdom in 2011 and reported with 95 % confidence intervals .
One thousand six hundred and fourteen VGKC-complex assays were requested for 1,298 patients between 2001 and 2011. VGKC-complex antibody titres [100 pM were detected in 57/1,298 patients (4.4 %), median age 59 years (25–77). Of these n = 17 had VGKC-complex titres [400 pM (17/1298; 1.3 %). There was an increase in the number of requests over this time, particularly after 2005 (Fig. 1), but the proportion of sera with VGKC-complex antibody titres [100 pM or 400 pM did not change appreciably between 2001 and 2005 and 2006–2011. Thirty-four of the 57 (60 %) patients presented with a classic VGKC-complex channelopathy, specifically peripheral nerve hyperexcitability (PNH; 21/57, 36.8 %) and/or limbic encephalitis (LE; 12/57 21 %). One patient had Morvan’s syndrome. The remaining patients (23/57, 40 %) had a wide range of central nervous system (CNS) and peripheral nervous system (PNS) disorders. The number of malignancies detected in patients (median age 59 years) with VGKC-complex antibodies (n = 7/57; 12 %) was significantly higher than the national cancer incidence reported in individuals aged 55–59 years (n = 699.6/100,000, 0.007 %) in the UK in 2011 (OR 19.9, 95 % CI 8.97–44.0 p \ 0.0001) .
Materials and methods
Number of Requests
been reported in some patients without a defined immunemediated syndrome [6–9]. Our institution provides a tertiary neurological service to approximately 3.5 million patients in the North West of England and North Wales but also includes a large number of patients with PNH reflecting the expertise of the late Dr. Ian Hart . The aim of this study was to analyse the clinical relevance of positive VGKC-complex antibodies in patients referred for testing.
Year Fig. 1 Proportion of VGKC-complex antibody results [100 or 400 pM 2001–2011
J Neurol (2015) 262:418–424
also more likely to receive immunotherapy compared to those with antibody titres \400 pM (Table 1; 76.5 vs. 25 % p = 0.0008) and a beneficial response was seen in 12/13 (92.3 %) treated patients. The rates of malignancy, however, did not differ significantly above or below a 400 pM cutoff (Table 1). Nine sera were available for further testing. LGI1 or CASPR2 antibodies were detected in LE (n = 2/3), PNH (n = 1/4), LE/PNH (n = 1/1) but not in the patient with Morvan’s syndrome. Contactin-2 antibodies were not detected in any sera tested. Further clinical details on these patients can be found in Table 2.
Table 1 Clinical and demographic features in patients with VGKCcomplex antibodies VGKC-complex \400 (n = 40) Age at presentation (yrs)
VGKC-complex [400 (n = 17)
20/40 (50 %)
VGKC-complex ab peak (pM)
Classic VGKCcomplex presentation
18/40 (45 %)
13/17 (76.5 %)
10/40 (25 %)
8/10 (80 %)
759 (437–4064) \0.0001c 16/17 (94.1 %)
2/17 (11.8 %)
5/40 (12.5 %)
13/17 (77 %)
12/13 (92.3 %)
Yrs years, ab antibody a
Student’s t test
Fisher’s exact test
VGKC-complex antibody association ***
Number of Patients
Fisher's exact test p =0.0004
30 20 10
VGKC-complex Ab Titre Fig. 2 Utility of VGKC-complex antibody 400 pM cutoff. VGKCcomplex antibody titres [400 pM were associated with classic VGKC-complex channelopathies
40/57 (70 %) patients had VGKC-complex antibody titres \400 pM. The median age of presentation was 54.5 years (25–76) with a male to female ratio of 1:1 (Table 1). Of these patients, 18/40 (45 %) had a classic VGKC-complex channelopathy (PNH; n = 15, LE; n = 3). The remaining patients had a range of CNS and/or PNS disorders detailed in Table 3. Ten out of 40 (25 %) patients were treated with immunotherapy (LE; n = 2, PNH; n = 2, CNS vasculitis; n = 1, Rasmussen’s encephalitis; n = 1, Guillain–Barre syndrome; n = 2, myasthenia gravis; n = 1, chronic inflammatory demyelinating polyneuropathy; n = 1) and 8/10 (80 %) improved, similar to the response rate seen in patients with antibody titres [400 pM (Table 1; 80 vs. 92.3 %, p = 0.56). Ten sera were available for testing by CBAs (LE; n = 2, PNH; n = 5, Rasmussen’s encephalitis; n = 1, multiple system atrophy; n = 1, and narcolepsy; n = 1). Only one patient with PNH and an associated malignant thymoma had CASPR2 antibodies but did not respond to immunotherapy. The remaining sera were negative by CBAs. Further clinical details for these patients can be found in Table 3. Limbic encephalitis The median age of presentation of LE was 63 years (47–77) with a male to female preponderance of 11:1. VGKC-complex antibody titres were between 133 and 4064 pM, mean 990 pM, and 9/12 (75 %) patients with LE had VGKC-complex titres [400 pM. Temporal lobe abnormalities with magnetic resonance imaging were detected in 67 % (8/12), abnormal electroencephalography in 64 % (7/11), hyponatraemia in 50 % (6/12), inflammatory CSF in 58 % (7/12), and sleep disturbance in 100 % (9/9). Of the five patients with a documented description of the seizures (partial seizures with or without secondary generalisation), semiology was not suggestive of faciobrachial dystonic seizures. No cases of LE were associated with malignancy. 11 patients with LE were treated with immunotherapy consisting of different combinations of intravenous methylprednisolone, intravenous immunoglobulin, and plasma exchange. All patients were reported to have improved following immunotherapy. PNH
VGKC-complex antibody titre \400 pM
The median age of presentation of PNH was 51 years (25–72) with a male to female ratio of 1:1. VGKCcomplex antibody titres were between 114 and 1064 pM, mean 360 pM although 15/22 (68 %) PNH patients had
LE limbic encephalitis, PNH peripheral nerve hyperexcitability, NMT neuromyotonia, NCS/EMG nerve conduction studies/electromyography, RRMS relapsing remitting multiple sclerosis, MG myasthenia gravis, SMN sersory motor neuropathy, Ab antibody, Nd not done, N normal, Ab neg negative for LGI1, CASPR2 contactin-2 antibodies, WC white blood cell, Pro protein, OCB oligoclonal bands, S serum, C cerebrospinal fluid
VGKC-complex antibody titres \400 pM. Electromyography (EMG) was supportive of PNH in 65 % (13/20) of cases. Three patients had a confirmed or suspected thymic malignancy. Symptomatic PNH treatment, most often with an anti-epileptic drug, was beneficial in 46 % (6/13) of patients. Four PNH patients received immunotherapy and at follow-up 1/2 patients appeared to have improved. Case study A case study illustrates that there is sometimes difficulty in relating VGKC-complex antibody levels to clinical features. A 54-year-old male patient presented with focal right facial neuromyotonia. Magnetic resonance imaging demonstrated an ipsilateral petrous apex cholesteatoma. Resection of the tumour led to a resolution of symptoms but also a decline in VGKC-complex antibody levels (Fig. 3). Symptoms subsequently recurred with an
elevation in VGKC-complex antibodies. Re-imaging demonstrated a recurrence of the cholesteatoma and a further resection was performed with sustained symptom resolution at last follow-up.
Discussion The aim of this study was to analyse the clinical relevance of positive VGKC-complex antibodies ([100 pM) requested on the basis of initial clinical suspicion. Titres [400 pM were associated with a classic VGKC-complex channelopathy, most commonly LE. PNH was more common with antibody titres \400 pM in addition to a wide range of CNS and PNS disorders. The clinical and paraclinical features of LE and PNH were in keeping with previous reports [4, 10] but LGI1 and CASPR2 antibodies were present in only 31 % (n = 5/16) of LE and PNH cases with sera available for testing.
Please see footnote to Table 2. SAN sensory axonal neuropathy, CNS central nervous system, SLE systemic lupus erythematosus, APS antiphospholipid syndrome, SSEP somatosensory evoked potentials, CRPS chronic regional pain syndrome, GBS Guillain–Barre´ syndrome, CIDP chronic inflammatory demyelinating polyneuropathy, VP ventriculoperitoneal, NPH normal pressure hydrocephalus, n/a not available
Temporal Relationship: VGKC and Treatment Symptom severity
VGKC-complex Ab Titre/pM
Importantly, all patients with LE responded to immunotherapy (this included some patients previously reported) . EMG was supportive of PNH in 65 % of cases. Just under half of the patients with PNH responded favourably to anti-epileptic drug treatment (most commonly lamotrigine) warranting a treatment trial in selected cases. Irrespective of titre, the incidence of malignancy was significantly higher than the reported national incidence of malignancy in a comparable age group. The utility of a VGKC-complex antibody titre[400 pM has been demonstrated in several retrospective studies [7– 9]. This study reiterates this finding but highlights an important association of PNH with antibody titres \ 400 pM as previously reported by Hart et al. . Morvan’s syndrome may also present with VGKC-complex titres \400 pM . The detection of LGI1 and CASPR2 antibodies by CBAs was highly specific for LE and PNH, but sera available for testing were limited. Comparable high rates of specificity for LGI1 and CASPR2 for LE have been reported in Paterson et al. (89 %), and Olberg et al. (90 %) [7, 8]. A more heterogeneous VGKC-complex antibody spectrum was seen in Klein et al. 2013 , but this could be explained by differences in the referral pattern with wider screening for VGKC-complex antibodies in that centre. Additionally, it is not uncommon to find patients with a classic VGKC-complex channelopathy in whom the antigen specificity is unknown (10–20 % of LE) [4, 9]. Sensitivity of current assay techniques and/or novel antigenic targets are plausible explanations. Ohkawa et al.  have reported novel surface antigens including DCC, DPP10, and ADAM23 but the pathogenicity of the antibodies requires further evidence. This study adds to the expanding group of heterogeneous disorders associated with titres \400 pM. In many
Time elapsed from 1st observation (weeks) Fig. 3 Case study. Right facial peripheral nerve hyperexcitability ipsilateral to petrous apex cholesteatoma. Arrows annotated with Rs denote surgical resection points
of these cases, the reason for the serological request was unclear and the presence of VGKC-complex antibodies was of doubtful clinical relevance. Despite this there was a significant response to immunotherapy due to the fact that many of these treated cases were of immune-mediated aetiology, e.g. Guillain–Barre syndrome, myasthenia gravis, chronic inflammatory demyelinating polyneuropathy, etc. There have been reports of low levels of VGKCcomplex antibodies (\400 pM), negative for LGI1 and CASPR2, in neurodegenerative conditions such as Creutzfeldt–Jakob disease, although in formal studies this was less than 5 % [15–17]. Although there may be situations where these antibodies contribute to the clinical phenotype, these observations suggest that VGKC-complex antibodies not associated with reactivity towards a known complex
antigen, may sometimes be incidental or secondary to neuronal damage. Clinical responses to immunotherapy can be helpful in supporting the clinical relevance but patients with a non-classical phenotype were less likely to receive immunotherapy. Thus, as seen here and in the other recent retrospective series many of the patients were treated conservatively [7, 8]. The difficulty in assessing the clinical relevance of VGKC-complex antibodies is illustrated by the case study. Cholesteatomas consist of keratinising squamous epithelium and endogenous expression of VGKCs to the best of our knowledge has not been reported, and yet the VGKCcomplex antibodies fell after removal of the tumour and rose again as it reappeared. Since the clinical features showed a similar time course, it is difficult to ascertain whether the change in antibodies or the removal of the local tumour was responsible for the clinical improvement. This study has several limitations. The study population was weighted towards PNH due to the local expertise of the late Dr. Hart but this does provide a comprehensive study of VGKC-complex antibody associated PNH. The retrospective design limited the extent of clinical information that could be attained, in particular treatment outcomes. The clinical utility of CBAs for LGI1, CASPR2, and Contactin-2 antibodies was difficult to assess due to the limited availability of sera for re-testing. Nevertheless, the results further support the use of a cutoff of 400 pM for VGKC-complex antibodies when assessing their relevance to the CNS presentation. A lower cutoff of 100 pM is helpful when considering a diagnosis of PNH, but the existence of antibodies in patients with other peripheral or central neurological disease needs to be appreciated. Malignancies are not uncommon with VGKCcomplex antibodies and screening should be considered. Acknowledgments The authors would like to thank Dr. Patrick Waters for providing the constructs used in the CBAs. The authors would also like to thank both Dr. Patrick Waters and Dr. Ester Coutinho for their helpful comments. Conflicts of interest SH is funded by a Watney/Myasthenia Gravis Association/Oxford Biomedical Research Centre Fellowship. AV and the University of Oxford hold patents and receive royalties and payments for autoantibody tests including VGKC-complex antibodies. SHW, PP, DO, and MS declare no conflicts of interest. Ethical standard The study was approved by the local institutional clinical governance and audit board and performed in accordance with the Helsinki Declaration of 1975, as revised in 2000 and 2008.
References 1. Eunson LH, Rea R, Zuberi SM, Youroukos S, Panayiotopoulos CP, Liguori R, Avoni P, McWilliam RC, Stephenson JB, Hanna MG, Kullmann DM, Spauschus A (2000) Clinical, genetic, and
J Neurol (2015) 262:418–424
expression studies of mutations in the potassium channel gene KCNA1 reveal new phenotypic variability. Ann Neurol 48:647–656 Browne DL, Gancher ST, Nutt JG, Brunt ER, Smith EA, Kramer P, Litt M (1994) Episodic ataxia/myokymia syndrome is associated with point mutations in the human potassium channel gene, KCNA1. Nat Genet 8:136–140 Zuberi SM, Eunson LH, Spauschus A, De Silva R, Tolmie NW, McWilliam RC, Stephenson JB, Kullmann DM, Hanna MG (1999) A novel mutation in the human voltage-gated potassium channel gene (Kv1.1) associates with episodic ataxia type 1 and sometimes with partial epilepsy. Brain 122:817–825 Irani SR, Alexander S, Waters P, Kleopa KA, Pettingill P, Zuliani L, Peles E, Buckley C, Lang B, Vincent A (2010) Antibodies to Kv1 potassium channel-complex proteins leucine-rich, glioma inactivated 1 protein and contactin-associated protein-2 in limbic encephalitis, Morvan’s syndrome and acquired neuromyotonia. Brain 133:2734–2748 Buckley C, Oger J, Clover L, Tu¨zu¨n E, Carpenter K, Jackson M, Vincent A (2001) Potassium channel antibodies in two patients with reversible limbic encephalitis. Ann Neurol 50:73–78 Vincent A, Buckley C, Schott JM, Baker I, Dewar K, Detert N, Clover L, Parkinson A, Bien C, Omer S, Lang B, Rossor M, Palace J (2004) Potassium channel antibody-associated encephalopathy: a potentially immunotherapy-responsive form of limbic encephalitis. Brain 127:701–712 Olberg H, Haugen M, Storstein A, Vedeler CA (2013) Neurological manifestations related to level of voltage-gated potassium channel antibodies. J Neurol Neurosurg Psychiatry 84:941–943 Paterson RW, Zandi MS, Armstrong R, Vincent A, Schott JM (2014) Clinical relevance of positive voltage-gated potassium channel (VGKC)-complex antibodies: experience from a tertiary referral centre. J Neurol Neurosurg Psychiatry 85:625–630 Klein CJ, Lennon VA, Aston PA, MCcKeon A, O’Toole O, Quek A, Pittock SJ (2013) Insights from LGI1 and CASPR2 potassium channel complex autoantibody subtyping. JAMA Neurol 70:229–234 Hart IK, Maddison P, Newsom-Davis J, Vincent A, Mills KR (2002) Phenotypic variants of autoimmune peripheral nerve hyperexcitability. Brain 125:1887–1895 Cancer Research UK (2014) Cancer incidence in the UK in 2011. http://publications.cancerresearchuk.org/downloads/Product/CS_ REPORT_INCIDENCE.pdf. Accessed 25 Oct 2014 Wong SH, Saunders MD, Larner AJ, Das K, Hart IK (2010) An effective immunotherapy regimen for VGKC antibody-positive limbic encephalitis. J Neurol Neurosurg Psychiatry 81:1167–1169 Ohkawa T, Fukata Y, Yamasaki M, Miyazaki T, Yokoi N, Takashima H, Watanabe M, Watanabe O, Fukata M (2013) Autoantibodies to epilepsy-related LGI1 limbic encephalitis neutralize LGI1-ADAM22 interaction and reduce synaptic AMPA receptors. J Neurosci 33:18161–18174 Irani SR, Pettingill P, Kleopa KA, Schiza N, Waters P, Mazia C, Zuliani L, Watanabe O, Lang B, Buckley C, Vincent A (2012) Morvan syndrome: clinical and serological observations in 29 cases. Ann Neurol 72:241–255 Fujita K, Yuasa T, Watanabe O, Takahashi Y, Hashiguchi S, Adachi K, Izumi Y, Kaji R (2012) Voltage-gated potassium channel complex antibodies in Creutzfeldt–Jakob disease. J Neurol 259:2249–2250 Angus-Leppan H, Rudge P, Mead S, Collinge J, Vincent A (2013) Autoantibodies in sporadic Creutzfeldt–Jakob disease. JAMA Neurol 70:919–992 Rossi M, Mead S, Collinge J, Rudge P, Vincent A (2014) Neuronal antibodies in patients with suspected or confirmed sporadic Creutzfeldt–Jakob disease. JNNP. doi:10.1136/jnnp-2014-308695
Complex rectovaginal fistulae are difficult to manage. With an initial failed attempt, a simple fistula becomes complex and the success rate of a subsequent repair decreases. A review of our prospectively maintained records over a period of 16 years
Encephalitis due to antibodies to voltage gated potassium channel (VGKC) typically presents with limbic encephalitis and medial temporal lobe involvement on neuroimaging. We describe a case of 13 year girl female with encephalitis due to antibodies t
We utilise a clinical case to highlight why exclusion of voltage-gated potassium channel (VGKC)-complex autoantibody testing in serological evaluation of patients may delay or miss the diagnosis. A 68-year-old man presented with increasing involuntar
Takayasu arteritis (TA) is an idiopathic large-vessel vasculitis affecting the aorta and its major branches. Although the disease rarely affects children, it does occur, even in infants. The objective of this study was to evaluate the clinical featur
Although autoantibodies targeted against voltage-gated potassium channel (VGKC)-associated proteins have been identified in limbic encephalitis (LE) and acquired neuromyotonia (aNMT), the role of these antibodies in disease pathophysiology has not be
Limbic encephalitis (LE) associated with antibodies to the voltage-gated potassium channel complex (VGKC) is a potentially reversible cause of cognitive impairment. Despite the prominence of cognitive dysfunction in this syndrome, little is known abo
Conventional therapy for neonatal necrotising fasciitis (NF) involves resuscitation and aggressive surgical debridement of necrotic tissue. This approach adds surgical stress in septicaemic neonates with low reserves. The present study reports a more
Conjoined twins are rare, with a reported incidence of 0.19 per 10,000 pregnancies in Europe. We discuss four spontaneous conjoined twin pregnancies presenting to a tertiary referral centre from 2005 to 2011, diagnosed on antenatal dating ultrasound.