Epidermolysis Bullosa Simplex with Mottled Pigmentation With

Research letter

Epidermolysis bullosa simplex with mottled or KRT14 gene encoding keratin 5 (K5) and keratin 14 (K14), pigmentation with noncicatricial alopecia: respectively.1,2 Dermatopathia pigmentosa reticularis (DPR), identiﬁcation of a recurrent p.P25L mutation in caused by a KRT14 mutation, is characterized by reticulate pig- KRT5 in four affected family members mentation, noncicatricial alopecia, onychodystrophia and loss of dermatoglyphics.3 Here, we report cases of EBS-MP with DOI: 10.1111/bjd.14083 noncicatricial alopecia, a clinical feature of DPR, with a recurrent p.P25L mutation in KRT5 in four Japanese family mem- DEAR EDITOR, Epidermolysis bullosa simplex with mottled pig- bers. mentation (EBS-MP) is a rare subtype of EBS that is character- A 28-year-old Japanese man (III-1) was referred to our ized by blistering, mottled pigmentation of the trunk and department with asymptomatic reticulate hyper- and hypopig- limbs, punctate hyperkeratosis of the palms and soles, and mentation on the trunk and extremities (Fig. 1a), hyperpig- dystrophic nails.1 EBS-MP is caused by a mutation in the KRT5 mented keratotic lesions on the volar edges (Fig. 1b),

(a) (b) (c) (d)

(e) (g)

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Fig 1. Clinical pictures of the proband (III-1): (a) asymptomatic, reticulate hyper- and hypopigmentation on the trunk and extremities; (b) hyperpigmented keratotic lesions on the volar edges; (c) punctate palmoplantar hyperkeratosis; and (d) hyperpigmented ﬁngers. Clinical pictures of patient III-2: (e) reticulate hyper- and hypopigmentation and (f) nonscarring alopecia. (g) The pedigree of the present Japanese family. Open symbols indicate unaffected individuals, black symbols indicate affected individuals, and the arrow indicates the proband.

© 2015 British Association of Dermatologists British Journal of Dermatology (2016) 174, pp633–635 633 634 Research letter punctate palmoplantar hyperkeratosis (Fig. 1c), hyperpig- atinocytes (arrows) (Fig. 2a), disorganized keratin filaments mented fingers (Fig. 1d) and noncicatricial alopecia. He (arrow), protrusion of the cytoplasm of the melanocytes shaved his head to hide the alopecia. Bullae emerged only on (fine arrow), and keratinocytes (dotted arrow) through the the palmoplantar areas until 2 years of age, and then the retic- discontinued basal lamina (Fig. 2b). Accumulated matured ulate hyper- and hypopigmentation had gradually developed melanosomes were detected in the melanocytes and ker- from childhood. His 25-year-old younger sister (III-2) atinocytes (Fig. 2b). Ultrastructural examination of the showed similar clinical features including reticulate hyper- adjacent hypopigmented area illustrated anomalous length- and hypopigmentation (Fig. 1e) and noncicatricial alopecia ened keratinocytes with dilated intercellular spaces (dotted (Fig. 1f). Bullae had emerged similarly. Their parents were arrow) and aberrantly localized melanocytes (arrows) nonconsanguineous. Their father (II-1) and grandmother (I-2) (Fig. 2c,d). Sparsely distributed matured melanosomes were had similar clinical features. Loss of dermatoglyphics was not detected in the melanocytes and keratinocytes (Fig. 2d). observed in all affected members of this family (Fig. 1c). The An electron microscopy examination of the hyperpig- family pedigree indicated an autosomal dominant genoder- mented keratotic area depicted anomalous polymorphous matosis (Fig. 1g). keratinocytes with dilated intercellular spaces (dotted Two biopsy specimens were taken from our patient (III- arrow), anomalous arch keratinocytes (fine arrow) adjacent 1), one from the boundary of the hyper- and hypopig- to the melanocytes, disorganized keratin filaments (bold mented area from the left forearm (Fig. 1a) and the other arrow), and detaching melanocytes (arrow) (Fig. 2e,f). from the border of the hyperpigmented keratotic and adja- Sparsely distributed matured melanosomes were detected in cent normal area of the left palmar edge (Fig. 1b). Elec- the melanocytes and keratinocytes (Fig. 2e). An ultrastruc- tron microscopy of the hyperpigmented area showed tural examination of the adjacent normal area showed no liquefaction degeneration-like vacuolization in the ker- typical abnormal structures.

(a) (c) (e)

(b) (d) (f)

Fig 2. Ultrastructural features of the proband’s lesional skin sample from (a,b) the hyperpigmented area, (c,d) the hypopigmented area and (e,f) the hyperpigmented keratotic area (a, c and e, original magnification 9 2000; b, d and f, original magnification 9 6000). (a) Liquefaction degeneration-like vacuolization (arrows). (b) Disorganized keratin filaments (arrow); protrusion of the cytoplasm of melanocytes (fine arrow) and that of keratinocytes (a dotted arrow) through the discontinued basal lamina. (c, d) Anomalous lengthened keratinocytes with dilated intercellular spaces (a dotted arrow) and aberrantly localized melanocytes (arrows). (e, f) Anomalous polymorphous keratinocytes with dilated intercellular spaces (dotted arrow), anomalous arch keratinocytes (fine arrow), disorganized keratin filaments (bold arrow), and detaching melanocytes (arrow). k, keratinocytes; m, melanocytes.

After ethical approval was granted by the Genetics Ethics of the K5/K14 pair, previously believed to be independent Committee of the Kinki University Faculty of Medicine, disorders. written informed consent was obtained from each of the 1 5 1 Divisions of Dermatology and Laboratory H. NAGAI four affected (I-2, II-1, III-1 and III-2) and three nonaf- 2 Medicine, Department of Internal Medicine, N. OISO fected (II-2, II-3 and II-4) family members in compliance 3 Kobe University Graduate School of S. TOMIDA with Declaration of Helsinki guidelines. We then performed 3 4 Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, K. SAKAI whole-exome sequencing as described previously, with a 1 Á Kobe 650-0017, Japan S. FUJIWARA mean depth of coverage of 94 2X. All four affected mem- 2 3 4 > Departments of Dermatology and Genome Y. NAKAMACHI bers had a recurrent c.74C T (p.P25L) missense mutation 5 Biology, Kinki University Faculty of S. KAWANO in KRT5. 2 Medicine, Osaka-Sayama, Japan A. KAWADA Using genomic DNA, we performed polymerase chain reac- 4 3 Department of Clinical Laboratory, Kobe K. NISHIO tion and direct sequencing (i) of the coding regions of KRT5 1 University Hospital, Kobe, Japan C. NISHIGORI and KRT14 in two affected members (II-1 and III-1) and (ii) E-mail: [email protected] independently on the exon including codon 25 in KRT5 in four affected and three unaffected family members, as H.N., N.O. and S.T. contributed equally to this work. described previously.5,6 We reconfirmed a recurrent c.74C>T (p.P25L) missense mutation in KRT5 in four affected members References only and no mutation in KRT14 in two affected members (II-1 and III-1). 1 Irvine AD, McKenna KE, Jenkinson H, Hughes AE. A mutation in the V1 domain of keratin 5 causes epidermolysis bullosa simplex We first suspected that our patient (III-1) had atypical with mottled pigmentation. J Invest Dermatol 1997; 108:809–10. EBS-MP, but the prominent reticulate hyper- and hypopigmen- 2 Harel A, Bergman R, Indelman M, Sprecher E. Epidermolysis bul- tation and noncicatricial alopecia required a differential diagno- losa simplex with mottled pigmentation resulting from a recurrent sis including DPR, Dowling–Degos disease, dyschromatosis mutation in KRT14. J Invest Dermatol 2006; 126:1654–7. universalis hereditaria, and the coincidental coexistence of 3 Lugassy J, Itin P, Ishida-Yamamoto A et al. Naegeli–Franceschetti– genetic hair disorders. It was necessary to explore why noncica- Jadassohn syndrome and dermatopathia pigmentosa reticularis: tricial alopecia was involved in all four family members. Thus, two allelic ectodermal dysplasias caused by dominant mutations in KRT14. Am J Hum Genet 2006; 79:724–30. we performed whole-exome sequencing in the family members 4 Takeichi T, Liu L, Fong K et al. Whole-exome sequencing to comprehensively identify any genetic anomalies. We improves mutation detection in a diagnostic epidermolysis bullosa detected a p.P25L mutation in KRT5 in all the affected members, laboratory. Br J Dermatol 2015; 172:94–100. and could not identify any other mutation in the candidate 5 Stephens K, Ehrlich P, Weaver M et al. Primers for exon-specific genes using whole-exome sequencing. The average depth of amplification of the KRT5 gene: identification of novel and recur- coverage in our study was 94Á2X, which is comparable with rent mutations in epidermolysis bullosa simplex patients. J Invest 108 – that of 91X observed in a well-known somatic genetic study of Dermatol 1997; :349 53. 6 Hut PHL, v d Vlies P, Jonkman MF et al. Exempting homologous lung adenocarcinoma.7 Using direct sequencing, we recon- pseudogene sequences from polymerase chain reaction amplifica- firmed a p.P25L mutation in KRT5 in all affected members and tion allows genomic keratin 14 hotspot mutation analysis. J Invest no mutation in KRT14 in two affected members. Dermatol 2000; 114:616–19. K5 and K14 form the primary keratin pair of epidermal 7 Imielinski M, Berger AH, Hammerman PS et al. Mapping the hall- keratinocytes and are strongly expressed in the basal layer marks of lung adenocarcinoma with massively parallel sequencing. and follicular outer root sheath.8 Keratins share a head–rod– Cell 2012; 150:1107–20. tail structural domain organization consisting of a central a- 8 Moll R, Divo M, Langbein L. The human keratins: biology and pathology. Histochem Cell Biol 2008; 129:705–33. helical rod domain flanked by two nonhelical domains, ter- 3,8 9 Irvine AD, Rugg EL, Lane EB et al. Molecular confirmation of the med the head and tail domains, respectively. K5/K14 ker- unique phenotype of epidermolysis bullosa simplex with mottled atin filaments are bundled as tonofilaments and attached to pigmentation. Br J Dermatol 2001; 144:40–5. desmosomes and hemidesmosomes. Keratin molecules carry- 10 Uttam J, Hutton E, Coulombe PA et al. The genetic basis of epider- ing K5-25L result in tonofilament clumping, suggesting that molysis bullosa simplex with mottled pigmentation. Proc Natl Acad the mutation affects the ability of keratin intermediate Sci U S A 1996; 93:9079–84. filaments to assemble properly.9 The keratin head domain is associated with melanosome transport, indicating that head Funding sources: This study was supported by a grant from domain mutations affect melanosome transportation ability.10 the Ministry of Health, Labour and Welfare of Japan (Health We surmised two possibilities in noncicatricial alopecia in and Labour Sciences Research Grant: Research on Intractable the affected family members: an unfocused common feature Diseases; H24-039) to N.O., and by a research grant from the in EBS-MP or a specific characteristic modified by unknown Japanese Society of Pigment Cell Research in 2013 to N.O. factors such as a modifier gene in the family members. Further accumulation of case series of EBS-MP and DPR may Conflicts of interest: none declared. provide more accurate diagnostic criteria for genetic disorders