A human keratin 10 knockout causes recessive epidermolytic hyperkeratosis

Epidermolytic hyperkeratosis (EHK) is a blistering skin disease inherited as an autosomal-dominant trait. The disease is caused by genetic defects of the epidermal keratin K1 or K10, leading to an impaired tonofilament network of differentiating epidermal cells. Here, we describe for the first time a kindred with recessive inheritance of EHK. Sequence analysis revealed a homozygous nonsense mutation of the KRT10 gene in the affected family members, leading to a premature termination codon (p.Q434X), whereas the clinically unaffected consanguineous parents were both heterozygous carriers of the mutation. Semi-quantitative RT-PCR and western blot analysis demonstrated degradation of the KRT10 transcript, resulting in complete absence of keratin K10 protein in the epidermis and cultured keratinocytes of homozygous patients. This K10 null mutation leads to a severe phenotype, clinically resembling autosomal-dominant EHK, but differing in form and distribution of keratin aggregates on ultrastructural analysis. Strong induction of the wound-healing keratins K6, K16 and K17 was found in the suprabasal epidermis, which are not able to compensate for the lack of keratin 10. We demonstrate that a recessive mutation in KRT10 leading to a complete human K10 knockout can cause EHK. Identification of the heterogeneity of this disorder has a major impact for the accurate genetic counseling of patients and their families and also has implications for gene-therapy approache

Mild recessive dystrophicepidermolysis bullosa associated with two compound heterozygous COL7A1 mutations

Dystrophic epidermolysis bullosa is a group of inherited skin blistering disorders caused by mutations in the COL7A1 gene coding for type VII collagen. More than 500 different COL7A1 mutations have been detected in dystrophic epidermolysis bullosa to date. Clarification of genotype-phenotype correlations is of particular importance for the development of novel therapeutic approaches. Here we report a female patient with mild dystrophic epidermolysis bullosa harbouring two compound heterozygous COL7A1 mutations, namely the intronic splice site mutation c.3832-2A > G and the glycine substitution p.G1347W. Our data extend the current knowledge on genotype-phenotype correlations in dystrophic epidermolysis bullosa