These articles have been accepted for publication in the British Journal of Dermatology and are currently being edited and typeset. Readers should note that articles published below have been fully refereed, but have not been through the copy-editing and proof correction process. Wiley-Blackwell and the British Association of Dermatologists cannot be held responsible for errors or consequences arising from the use of information contained in these articles; nor do the views and opinions expressed necessarily reflect those of Wiley-Blackwell or the British Association of Dermatologists This article is protected by copyright. All rights reserved. Received Date : 20-May-2014 Revised Date : 04-Sep-2014 Accepted Date : 07-Sep-2014 Article type
: Item of Correspondence
Two novel mutations in the LOR gene in three families with loricrin keratoderma
A. Hotz1, E. Bourrat2, I. Hausser3, M. Haftek4, M. V. da Silva5, J. Fischer1 1
Institute of Human Genetics, University Medical Center Freiburg, Freiburg, Germany Centre de Reference des Genodermatoses, Hôpital Saint-Louis, Paris, France 3 Institute of Pathology, University Hospital of Heidelberg, Heidelberg, Germany 4 University Lyon 1, EA4169 and CNRS, Lyon, France 5 Dermatology Service at Santa Casa de Misericórdia de Porto Alegre, Porto Alegre (RS), Brazil. 2
Corresponding author: Prof. Dr. med. Dr. Judith Fischer Institute of Human Genetics University Medical Center Freiburg Breisacherstraße 33, 79106 Freiburg, GERMANY Tel.: +49 (0)761-270-70510 Fax: +49 (0)761-270-70410 [email protected] Running head: Novel mutations in the LOR gene in loricrin keratoderma Key words: loricrin keratoderma, LOR, ichthyosis, palmoplantar keratoderma, Vohwinkel syndrome Funding source: This study was supported by the Institute of Human Genetics at the University Medical Center Freiburg. I. Hausser was supported by a BMBF grant (NIRK 016GM0904). Conflicts of interest: None declared
This article is protected by copyright. All rights reserved. Loricrin keratoderma (LK, MIM #604117) is an autosomal dominant disorder characterized by honeycomb palmoplantar keratoderma (PPK) and generalized mild ichthyosis, often associated with pseudoainhum. LK is caused by heterozygous mutations in the LOR gene (MIM *152445). Eleven families with LK with four different LOR mutations have been reported to date.1-11 Here we report two novel LOR mutations in four patients with LK. Patient 1 is a 21-year-old woman of Caucasian origin. She was born as a collodion baby (CB) and has developed transgredient honeycomb-like PPK with mild digital constrictions, generalized moderate ichthyosis without erythema and with hyperkeratosis in body folds (Fig. 1a-c). Ultrastructural investigation of a skin biopsy from the wrist showed intranuclear inclusions within the granular layer keratinocytes (Fig. 1f-g). As revealed with immunogold labelling, these inclusions contained loricrin. Similar, although less prominent, electrondense inclusions may also be observed in the granular layer keratinocyte nuclei in normal human ridged skin of palms and soles. However, such inclusions were not labelled with an anti-loricrin antibody in our control samples (supplementary Fig. S1); in healthy individuals, this antibody recognized only loricrin associated with CE. Patient 2 (29-year-old man) and patient 3 (his 68-year-old mother, Brazilian origin) were born as CBs with mild generalized congenital non-erythrodermic ichthyosis. The mother developed mild diffuse scales, well-demarcated symmetric yellow PPK without erythematous borders and with constricting bands encircling the fingers, but no real honeycomb-like PPK. Skin biopsy from a keratodermic region revealed a thickened, orthokeratotic stratum corneum. The biopsy from an ichthyotic region revealed a normally structured epidermis with a slightly parakeratotic stratum corneum. The son showed the same, but less severe phenotype than his mother (Fig. 1d-e). Patient 4 is a 64-year-old woman from Brazil with transgredient diffuse PPK with onset in childhood, pseudoainhum at the left fifth toe and generalized ichthyosiform dermatosis. Skin biopsy revealed hyperkeratosis with orthokeratosis and parakeratosis. Patient 4 belongs to the third out of five generations which are affected with LK.12 We found two novel heterozygous mutations in exon 2 of the LOR gene, c.646_647insGCAGCAGGTC, p.Gln216Argfs*123 in patient 1 and c.798_799dupT, p.Gly267Trpfs*69 in patient 2, 3 and 4. Both mutations lead to a frameshift and an elongated loricrin protein because of delayed termination. The new stop codon is at the same position as in the previously reported mutations. The new protein is 22 amino acids (patient 1) or 25 amino acids (patients 2-4) longer than wild type protein. All of the previously reported mutations are single base pair insertions. The most frequent insertion mutation, 730insG, has been found in 8 families from different ethnic backgrounds 1-8 (Table 1), so a founder effect can be excluded. It has been suggested that this mutation is a hotspot mutation. The mutations 730insG, 709insC9 and 578insG11 are localized in a stretch of several identical nucleotides, which might be susceptible to mutagenesis via slippage during replication.5 Only the mutations 662insT10 and c.798_799dupT are duplications of a single T nucleotide. C.798_799dupT (patients 2-4) is downstream from all previously reported mutations. Since patients 2-4 are of Brazilian origin, a founder effect cannot be excluded. The inserted nucleotides in our mutation c.646_647insGCAGCAGGTC are identical to the sequence at position c.633_642.
This article is protected by copyright. All rights reserved. The phenotype of LK can be very heterogeneous. We found no correlation between phenotype and the position and type of the mutation. Variations in severity of the phenotype could be explained by different expression of the LOR gene or other genetic factors such as intragenic polymorphisms or other modifier genes. CBs were described in nearly half of the reported cases of LK (Table 1). This feature can thus be the first manifestation of LK, and it is appropriate to add LK to the differential diagnoses of this phenotype. Wild-type loricrin protein was reported to be distributed throughout the upper epidermal cells, including both cytoplasm and nucleus, but mutant loricrin protein was localized only within the nucleus.11 In previously published investigations, the AF62 antibody to loricrin had produced a diffuse staining over the cytoplasm and nuclei, with an additional concentration over the granular intranuclear inclusions. Nuclear localization sequences (NLS), which target proteins into the nucleus, contain the basic amino acids lysine and arginine. Our mutations, as well as the previously reported mutations change the Gly-Lys-rich domain into an ArgLeu-rich terminal domain.1,6 Mutant loricrin is rich in arginine and, therefore, the mutant Cterminus is predicted to contain a NLS.2,6 In our patient 1, the intranuclear loricrin was immunolocalized exclusively within the granular deposits and did not associate with the nucleoplasm or the nucleoli (Fig. 1f-g). The AF62 antibody raised against a C-terminal peptide of wild type loricrin is not supposed to detect the mutant versions with modified Cterminal sequence. Therefore, observation of the labelling within the intranuclear granules in the lesional skin of patient 1, but not in the healthy control, suggests that nuclear translocation of mutant loricrin is accompanied by displacement of native protein into the deposits. Indeed, cross-linking between loricrin molecules precedes their incorporation into the cornified cell envelopes (CE) and the mutant/native hetero oligomers may occur. Loricrin draining into the nuclei may result in a relative shortage of the protein in the cytoplasm and, therefore, its decreased presence in the CE. Also, accumulation of loricrin in the nuclei might interfere with the nuclear autolytic process during the terminal differentiation of keratinocytes.2 In summary, we report two novel mutations in the LOR gene in three families. Our report extends the repertoire of loricrin mutations in LK and contributes to a better understanding of the clinical and genetic heterogeneity in this rare disease. Materials and Methods Genomic DNA was isolated from peripheral blood of the patients using standard protocols. The loricrin gene consists of two exons, the second exon contains the entire coding sequence. We used the reference sequence NM_000427.2. Primer sequences and reaction conditions are available on request. PCR products were purified and directly sequenced by use of the ABI PRISMTM Dye Terminator Cycle Sequencing Kit. They were analysed on an ABI 3500 DNA Sequencer (Applied Biosystems, Foster City, USA). For immunoelectron microscopy we used the AF62 polyclonal rabbit antibody (1/500; BAbCo, Richmond, CA), produced against a C-terminal peptide from the Mouse loricrin sequence, which recognizes both Human and Mouse loricrin. Immunogold labelling was performed on ultrathin sections of Lowicryl K4M –embedded skin samples using goat antirabbit IgG colloidal gold conjugate (1/10; GAR G5; BBI, Cardiff, UK).
This article is protected by copyright. All rights reserved. Acknowledgments The authors are grateful to the patients and their families for supporting this study. We would like to thank Susan Cure for critical comments on the manuscript. Electron microscopy samples were observed at the Centre Technologique des Microstructures (CTµ), a Lyon Bio Image facility of the Lyon 1 University, France.
References 1
Maestrini E, Monaco AP, McGrath JA, Ishida-Yamamoto A, Camisa C, Hovnanian A, Weeks DE, Lathrop M, Uitto J, Christiano AM. A molecular defect in loricrin, the major component of the cornified cell envelope, underlies Vohwinkel's syndrome. Nat Genet 1996; 13:70-7.
2
Korge BP, Ishida-Yamamoto A, Pünter C, Dopping-Hepenstal PJ, Iizuka H, Stephenson A, Eady RA, Munro CS. Loricrin mutation in Vohwinkel's keratoderma is unique to the variant with ichthyosis. J Invest Dermatol 1997; 109:604-10.
3
Takahashi H, Ishida-Yamamoto A, Kishi A, Ohara K, Iizuka H. Loricrin gene mutation in a Japanese patient of Vohwinkel's syndrome. J Dermatol Sci 1999; 19:44-7.
4
Matsumoto K, Muto M, Seki S, Saida T, Horiuchi N, Takahashi H, Ishida-Yamamoto A, Iizuka H. Loricrin keratoderma: a cause of congenital ichthyosiform erythroderma and collodion baby. Br J Dermatol 2001; 145:657-60.
5
O'Driscoll J, Muston GC, McGrath JA, Lam HM, Ashworth J, Christiano AM. A recurrent mutation in the loricrin gene underlies the ichthyotic variant of Vohwinkel syndrome. Clin Exp Dermatol 2002; 27:243-6.
6
Gedicke MM, Traupe H, Fischer B, Tinschert S, Hennies HC. Towards characterization of palmoplantar keratoderma caused by gain-of-function mutation in loricrin: analysis of a family and review of the literature. Br J Dermatol 2006; 154:167-71.
7
Drera B, Tadini G, Balbo F, Marchese L, Barlati S, Colombi M. De novo occurrence of the 730insG recurrent mutation in an Italian family with the ichthyotic variant of Vohwinkel syndrome, loricrin keratoderma. Clin Genet 2008; 73:85-8.
8
Yeh JM, Yang MH, Chao SC. Collodion baby and loricrin keratoderma: a case report and mutation analysis. Clin Exp Dermatol 2013; 38:147-50.
9
Ishida-Yamamoto A, McGrath JA, Lam H, Iizuka H, Friedman RA, Christiano AM. The molecular pathology of progressive symmetric erythrokeratoderma: a frameshift mutation in the loricrin gene and perturbations in the cornified cell envelope. Am J Hum Genet 1997; 61:581-9.
10 Armstrong DK, McKenna KE, Hughes AE. A novel insertional mutation in loricrin in Vohwinkel's Keratoderma. J Invest Dermatol 1998; 111:702-4.
This article is protected by copyright. All rights reserved.
11 Song S, Shen C, Song G, Mao X, Yan G, Wang X, Yan M, Zhong N. A novel c.545546insG mutation in the loricrin gene correlates with a heterogeneous phenotype of loricrin keratoderma. Br J Dermatol 2008; 159:714-9. 12 Corte LD, da Silva MV, de Oliveira CF, Vetoratto G, Steglich RB, Borges J. Vohwinkel syndrome, ichthyosiform variant – by Camisa – case report. An Bras Dermatol 2013; 88:206-8.
Figure legends: Fig. 1. Clinical features in patient 1 include honeycomb-like PPK, hyperkeratosis in elbows and mild digital constrictions (a-c). PPK in patient 2 (d) and patient 3 (e). Immunoelectron microscopy in patient 1: intranuclear electron-dense inclusions within a granular layer keratinocyte (f), labelled with an anti-loricrin antibody. (g) A higher power picture of the nucleus framed in (f) shows abnormal deposition of loricrin. Asterisks indicate keratohyalin granules. The inactive, homogeneous nucleolus and nucleoplasm remain free of the label. Bars = 1 µm in (f); 200 nm in (g).
Supplementary Fig. S1. Control immunogold labelling on normal ridged skin sections (human fingertip) demonstrates the absence of nuclear localization of native loricrin (a, b) and association of the latter with cornified envelopes of the stratum granulosum keratinocytes (c). b) A higher magnification of the electron-dense inclusions in the nucleus (N). Asterisks indicate keratohyalin granules. Bars = 0.5 µm in (a); 200 nm in (b and c).
Table 1: Clinical features of families with loricrin keratoderma
+
+
+
+
+
+
+
-
2
3
UK UK (Scotla nd) Japan
Hone ycom blike +
+
+
+
+
-
3
4
Japan
+
+
+
+
+
Hearing impairment Well-demarcated symmetrical keratoderma of palmes and soles; generalized diffuse erythema Generalized ichthyosiform erythroderma Increased skin marking on the knuckles Well-demarcated erythematous plaques Well-demarcated erythematous plaques Hyperkeratosis over the
Fa mil y no.
Gene mutation
1 2
5
730insG1
6 7 8 9 10
Ethnic backgr ound
UK Germa ny
Ichth yosis
Palmop lantar keratod erma
Pseudoainhu m and/or autoamputation
Collo dion baby
Special skin abnormalities/other features
Refere nce
+
-
-
1
+
+
+
+
-
+
+
+
-
+
Italy
+
+
+
+
-
Taiwan
+
+
+
+
+
1
Japan
+
+
+
+
-
1
UK (NI)
+
+
+
+
-
709insC 662insT
4 5 6 7 8 9 10
This article is protected by copyright. All rights reserved. knuckles 11
12
578insG1 (c.545_54 6insG)2 c.646_647 ins GCAGCA GGTC2
13 c.798_799 dupT2 14 1
China
+
+
-
-
-
Severe hyperkeratosis on dorsal parts of hands
11
France (Cauca sian)
+
+
+
+
+
Yellow and more severe hyperkeratosis in body folds
present study (Pat. 1)
France (Brazili an)
+
+
-
+
+
-
Brazil
+
+
-
+
-
-
previously used transcript, 2 actually used transcript
present study (Pat. 2+3) 12 and present study (Pat. 4)
This article is protected by copyright. All rights reserved.
: Item of Correspondence
Two novel mutations in the LOR gene in three families with loricrin keratoderma
A. Hotz1, E. Bourrat2, I. Hausser3, M. Haftek4, M. V. da Silva5, J. Fischer1 1
Institute of Human Genetics, University Medical Center Freiburg, Freiburg, Germany Centre de Reference des Genodermatoses, Hôpital Saint-Louis, Paris, France 3 Institute of Pathology, University Hospital of Heidelberg, Heidelberg, Germany 4 University Lyon 1, EA4169 and CNRS, Lyon, France 5 Dermatology Service at Santa Casa de Misericórdia de Porto Alegre, Porto Alegre (RS), Brazil. 2
Corresponding author: Prof. Dr. med. Dr. Judith Fischer Institute of Human Genetics University Medical Center Freiburg Breisacherstraße 33, 79106 Freiburg, GERMANY Tel.: +49 (0)761-270-70510 Fax: +49 (0)761-270-70410 [email protected] Running head: Novel mutations in the LOR gene in loricrin keratoderma Key words: loricrin keratoderma, LOR, ichthyosis, palmoplantar keratoderma, Vohwinkel syndrome Funding source: This study was supported by the Institute of Human Genetics at the University Medical Center Freiburg. I. Hausser was supported by a BMBF grant (NIRK 016GM0904). Conflicts of interest: None declared
This article is protected by copyright. All rights reserved. Loricrin keratoderma (LK, MIM #604117) is an autosomal dominant disorder characterized by honeycomb palmoplantar keratoderma (PPK) and generalized mild ichthyosis, often associated with pseudoainhum. LK is caused by heterozygous mutations in the LOR gene (MIM *152445). Eleven families with LK with four different LOR mutations have been reported to date.1-11 Here we report two novel LOR mutations in four patients with LK. Patient 1 is a 21-year-old woman of Caucasian origin. She was born as a collodion baby (CB) and has developed transgredient honeycomb-like PPK with mild digital constrictions, generalized moderate ichthyosis without erythema and with hyperkeratosis in body folds (Fig. 1a-c). Ultrastructural investigation of a skin biopsy from the wrist showed intranuclear inclusions within the granular layer keratinocytes (Fig. 1f-g). As revealed with immunogold labelling, these inclusions contained loricrin. Similar, although less prominent, electrondense inclusions may also be observed in the granular layer keratinocyte nuclei in normal human ridged skin of palms and soles. However, such inclusions were not labelled with an anti-loricrin antibody in our control samples (supplementary Fig. S1); in healthy individuals, this antibody recognized only loricrin associated with CE. Patient 2 (29-year-old man) and patient 3 (his 68-year-old mother, Brazilian origin) were born as CBs with mild generalized congenital non-erythrodermic ichthyosis. The mother developed mild diffuse scales, well-demarcated symmetric yellow PPK without erythematous borders and with constricting bands encircling the fingers, but no real honeycomb-like PPK. Skin biopsy from a keratodermic region revealed a thickened, orthokeratotic stratum corneum. The biopsy from an ichthyotic region revealed a normally structured epidermis with a slightly parakeratotic stratum corneum. The son showed the same, but less severe phenotype than his mother (Fig. 1d-e). Patient 4 is a 64-year-old woman from Brazil with transgredient diffuse PPK with onset in childhood, pseudoainhum at the left fifth toe and generalized ichthyosiform dermatosis. Skin biopsy revealed hyperkeratosis with orthokeratosis and parakeratosis. Patient 4 belongs to the third out of five generations which are affected with LK.12 We found two novel heterozygous mutations in exon 2 of the LOR gene, c.646_647insGCAGCAGGTC, p.Gln216Argfs*123 in patient 1 and c.798_799dupT, p.Gly267Trpfs*69 in patient 2, 3 and 4. Both mutations lead to a frameshift and an elongated loricrin protein because of delayed termination. The new stop codon is at the same position as in the previously reported mutations. The new protein is 22 amino acids (patient 1) or 25 amino acids (patients 2-4) longer than wild type protein. All of the previously reported mutations are single base pair insertions. The most frequent insertion mutation, 730insG, has been found in 8 families from different ethnic backgrounds 1-8 (Table 1), so a founder effect can be excluded. It has been suggested that this mutation is a hotspot mutation. The mutations 730insG, 709insC9 and 578insG11 are localized in a stretch of several identical nucleotides, which might be susceptible to mutagenesis via slippage during replication.5 Only the mutations 662insT10 and c.798_799dupT are duplications of a single T nucleotide. C.798_799dupT (patients 2-4) is downstream from all previously reported mutations. Since patients 2-4 are of Brazilian origin, a founder effect cannot be excluded. The inserted nucleotides in our mutation c.646_647insGCAGCAGGTC are identical to the sequence at position c.633_642.
This article is protected by copyright. All rights reserved. The phenotype of LK can be very heterogeneous. We found no correlation between phenotype and the position and type of the mutation. Variations in severity of the phenotype could be explained by different expression of the LOR gene or other genetic factors such as intragenic polymorphisms or other modifier genes. CBs were described in nearly half of the reported cases of LK (Table 1). This feature can thus be the first manifestation of LK, and it is appropriate to add LK to the differential diagnoses of this phenotype. Wild-type loricrin protein was reported to be distributed throughout the upper epidermal cells, including both cytoplasm and nucleus, but mutant loricrin protein was localized only within the nucleus.11 In previously published investigations, the AF62 antibody to loricrin had produced a diffuse staining over the cytoplasm and nuclei, with an additional concentration over the granular intranuclear inclusions. Nuclear localization sequences (NLS), which target proteins into the nucleus, contain the basic amino acids lysine and arginine. Our mutations, as well as the previously reported mutations change the Gly-Lys-rich domain into an ArgLeu-rich terminal domain.1,6 Mutant loricrin is rich in arginine and, therefore, the mutant Cterminus is predicted to contain a NLS.2,6 In our patient 1, the intranuclear loricrin was immunolocalized exclusively within the granular deposits and did not associate with the nucleoplasm or the nucleoli (Fig. 1f-g). The AF62 antibody raised against a C-terminal peptide of wild type loricrin is not supposed to detect the mutant versions with modified Cterminal sequence. Therefore, observation of the labelling within the intranuclear granules in the lesional skin of patient 1, but not in the healthy control, suggests that nuclear translocation of mutant loricrin is accompanied by displacement of native protein into the deposits. Indeed, cross-linking between loricrin molecules precedes their incorporation into the cornified cell envelopes (CE) and the mutant/native hetero oligomers may occur. Loricrin draining into the nuclei may result in a relative shortage of the protein in the cytoplasm and, therefore, its decreased presence in the CE. Also, accumulation of loricrin in the nuclei might interfere with the nuclear autolytic process during the terminal differentiation of keratinocytes.2 In summary, we report two novel mutations in the LOR gene in three families. Our report extends the repertoire of loricrin mutations in LK and contributes to a better understanding of the clinical and genetic heterogeneity in this rare disease. Materials and Methods Genomic DNA was isolated from peripheral blood of the patients using standard protocols. The loricrin gene consists of two exons, the second exon contains the entire coding sequence. We used the reference sequence NM_000427.2. Primer sequences and reaction conditions are available on request. PCR products were purified and directly sequenced by use of the ABI PRISMTM Dye Terminator Cycle Sequencing Kit. They were analysed on an ABI 3500 DNA Sequencer (Applied Biosystems, Foster City, USA). For immunoelectron microscopy we used the AF62 polyclonal rabbit antibody (1/500; BAbCo, Richmond, CA), produced against a C-terminal peptide from the Mouse loricrin sequence, which recognizes both Human and Mouse loricrin. Immunogold labelling was performed on ultrathin sections of Lowicryl K4M –embedded skin samples using goat antirabbit IgG colloidal gold conjugate (1/10; GAR G5; BBI, Cardiff, UK).
This article is protected by copyright. All rights reserved. Acknowledgments The authors are grateful to the patients and their families for supporting this study. We would like to thank Susan Cure for critical comments on the manuscript. Electron microscopy samples were observed at the Centre Technologique des Microstructures (CTµ), a Lyon Bio Image facility of the Lyon 1 University, France.
References 1
Maestrini E, Monaco AP, McGrath JA, Ishida-Yamamoto A, Camisa C, Hovnanian A, Weeks DE, Lathrop M, Uitto J, Christiano AM. A molecular defect in loricrin, the major component of the cornified cell envelope, underlies Vohwinkel's syndrome. Nat Genet 1996; 13:70-7.
2
Korge BP, Ishida-Yamamoto A, Pünter C, Dopping-Hepenstal PJ, Iizuka H, Stephenson A, Eady RA, Munro CS. Loricrin mutation in Vohwinkel's keratoderma is unique to the variant with ichthyosis. J Invest Dermatol 1997; 109:604-10.
3
Takahashi H, Ishida-Yamamoto A, Kishi A, Ohara K, Iizuka H. Loricrin gene mutation in a Japanese patient of Vohwinkel's syndrome. J Dermatol Sci 1999; 19:44-7.
4
Matsumoto K, Muto M, Seki S, Saida T, Horiuchi N, Takahashi H, Ishida-Yamamoto A, Iizuka H. Loricrin keratoderma: a cause of congenital ichthyosiform erythroderma and collodion baby. Br J Dermatol 2001; 145:657-60.
5
O'Driscoll J, Muston GC, McGrath JA, Lam HM, Ashworth J, Christiano AM. A recurrent mutation in the loricrin gene underlies the ichthyotic variant of Vohwinkel syndrome. Clin Exp Dermatol 2002; 27:243-6.
6
Gedicke MM, Traupe H, Fischer B, Tinschert S, Hennies HC. Towards characterization of palmoplantar keratoderma caused by gain-of-function mutation in loricrin: analysis of a family and review of the literature. Br J Dermatol 2006; 154:167-71.
7
Drera B, Tadini G, Balbo F, Marchese L, Barlati S, Colombi M. De novo occurrence of the 730insG recurrent mutation in an Italian family with the ichthyotic variant of Vohwinkel syndrome, loricrin keratoderma. Clin Genet 2008; 73:85-8.
8
Yeh JM, Yang MH, Chao SC. Collodion baby and loricrin keratoderma: a case report and mutation analysis. Clin Exp Dermatol 2013; 38:147-50.
9
Ishida-Yamamoto A, McGrath JA, Lam H, Iizuka H, Friedman RA, Christiano AM. The molecular pathology of progressive symmetric erythrokeratoderma: a frameshift mutation in the loricrin gene and perturbations in the cornified cell envelope. Am J Hum Genet 1997; 61:581-9.
10 Armstrong DK, McKenna KE, Hughes AE. A novel insertional mutation in loricrin in Vohwinkel's Keratoderma. J Invest Dermatol 1998; 111:702-4.
This article is protected by copyright. All rights reserved.
11 Song S, Shen C, Song G, Mao X, Yan G, Wang X, Yan M, Zhong N. A novel c.545546insG mutation in the loricrin gene correlates with a heterogeneous phenotype of loricrin keratoderma. Br J Dermatol 2008; 159:714-9. 12 Corte LD, da Silva MV, de Oliveira CF, Vetoratto G, Steglich RB, Borges J. Vohwinkel syndrome, ichthyosiform variant – by Camisa – case report. An Bras Dermatol 2013; 88:206-8.
Figure legends: Fig. 1. Clinical features in patient 1 include honeycomb-like PPK, hyperkeratosis in elbows and mild digital constrictions (a-c). PPK in patient 2 (d) and patient 3 (e). Immunoelectron microscopy in patient 1: intranuclear electron-dense inclusions within a granular layer keratinocyte (f), labelled with an anti-loricrin antibody. (g) A higher power picture of the nucleus framed in (f) shows abnormal deposition of loricrin. Asterisks indicate keratohyalin granules. The inactive, homogeneous nucleolus and nucleoplasm remain free of the label. Bars = 1 µm in (f); 200 nm in (g).
Supplementary Fig. S1. Control immunogold labelling on normal ridged skin sections (human fingertip) demonstrates the absence of nuclear localization of native loricrin (a, b) and association of the latter with cornified envelopes of the stratum granulosum keratinocytes (c). b) A higher magnification of the electron-dense inclusions in the nucleus (N). Asterisks indicate keratohyalin granules. Bars = 0.5 µm in (a); 200 nm in (b and c).
Table 1: Clinical features of families with loricrin keratoderma
+
+
+
+
+
+
+
-
2
3
UK UK (Scotla nd) Japan
Hone ycom blike +
+
+
+
+
-
3
4
Japan
+
+
+
+
+
Hearing impairment Well-demarcated symmetrical keratoderma of palmes and soles; generalized diffuse erythema Generalized ichthyosiform erythroderma Increased skin marking on the knuckles Well-demarcated erythematous plaques Well-demarcated erythematous plaques Hyperkeratosis over the
Fa mil y no.
Gene mutation
1 2
5
730insG1
6 7 8 9 10
Ethnic backgr ound
UK Germa ny
Ichth yosis
Palmop lantar keratod erma
Pseudoainhu m and/or autoamputation
Collo dion baby
Special skin abnormalities/other features
Refere nce
+
-
-
1
+
+
+
+
-
+
+
+
-
+
Italy
+
+
+
+
-
Taiwan
+
+
+
+
+
1
Japan
+
+
+
+
-
1
UK (NI)
+
+
+
+
-
709insC 662insT
4 5 6 7 8 9 10
This article is protected by copyright. All rights reserved. knuckles 11
12
578insG1 (c.545_54 6insG)2 c.646_647 ins GCAGCA GGTC2
13 c.798_799 dupT2 14 1
China
+
+
-
-
-
Severe hyperkeratosis on dorsal parts of hands
11
France (Cauca sian)
+
+
+
+
+
Yellow and more severe hyperkeratosis in body folds
present study (Pat. 1)
France (Brazili an)
+
+
-
+
+
-
Brazil
+
+
-
+
-
-
previously used transcript, 2 actually used transcript
present study (Pat. 2+3) 12 and present study (Pat. 4)
This article is protected by copyright. All rights reserved.
