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Case Reports
. 2020 Nov;8(11):e1457.
doi: 10.1002/mgg3.1457. Epub 2020 Sep 2.

The first case of a mosaic superficial epidermolytic ichthyosis diagnosed by Ultra-Deep Sequence

Yue Li  1   2 , Ruhong Cheng  1   2 , Jianying Liang  1   2 , Zhirong Yao  1   2   3 , Ming Li  1   2   3
Affiliations
Case Reports

The first case of a mosaic superficial epidermolytic ichthyosis diagnosed by Ultra-Deep Sequence

Yue Li et al. Mol Genet Genomic Med. 2020 Nov.

Abstract

Background: Superficial epidermolytic ichthyosis (SEI), known as ichthyosis bullosa of Siemens (IBS; OMIM No. 146800) before, is a type of keratinopathic ichthyosis due to the KRT2 mutations (NM_000423.3; OMIM No. 600194). Here, we report the first case of SEI caused by a KRT2 mosaic mutation.

Methods: We presented the clinical data of a 5-year-old Chinese boy who suffered from SEI. The histopathological examination and immunofluorescence were performed to rule out immunobullous skin diseases and diseases with subepidermal blisters. Genomic DNA samples were extracted from the lesion tissue and next-generation sequencing was performed. We also confirmed the variant allele frequency (VAF) in different tissues by an Ultra-Deep Sequencing technology.

Results: The patient presented with blisters on the lower extremities and linear, superficially hyperkeratotic lesions. Immunofluorescence of IgG, IgA, IgM, C3, C4, and C1q were negative, and the histopathological results showed intraepidermal blisters containing lymphocytes and eosinophils. A heterozygous missense mutation, c.G1459A (p. Glu487Lys), in exon 7 of the KRT2 gene was detected at a 31.17% allele frequency. The same mutation p. Glu487Lys has been described several times in the literature.

Conclusion: Thus, in our patient, the mosaic mutation explains the blaschkoid ichthyosiform phenotype. To our knowledge, this is the first case of SEI with a KRT2 mosaic mutation.

Keywords: KRT2; Ultra-Deep Sequence; somatic mosaicism; superficial epidermolytic ichthyosis.

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Conflict of interest statement

All authors state that no financial and personal relationships with other people or organizations that could inappropriately influence (bias) their work.

Figures

FIGURE 1
FIGURE 1
(a,b) A small number of linear hyperkeratotic lesions on the trunk. (c,d) Greyish‐brown linear hyperkeratotic lesions on the buttocks. (e) Hyperkeratotic plaques and focal areas of peeling (Mauserung phenomenon) on the left foot. (f,g) Pustules and blisters on the upper and lower extremities. (h) Lesion tissue from which DNA was extracted.
FIGURE 2
FIGURE 2
(a) Intraepidermal blisters containing lymphocytes and eosinophils (original magnification, ×50). (b,c) the intercellular separation (original magnification, ×250, ×500).
FIGURE 3
FIGURE 3
(a) The variant allele frequencies in different samples. (b) Direct sequencing of the probands showing a heterozygous mutation of c.G1459A in exon 7 of the KRT2 gene.
See this image and copyright information in PMC

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