SNP Shot: Genomic Insights

Epidermolytic hyperkeratosis (EHK) is a congenital skin condition evident from birth. Newborns with EHK often exhibit widespread redness of the skin (erythroderma) and pronounced blistering. Due to the compromised protective function of their skin, these infants are susceptible to dehydration and systemic or skin infections (sepsis).

With age, the blistering in individuals with EHK tends to decrease, erythroderma becomes less pronounced, and the skin thickens (hyperkeratosis). This thickening is particularly noticeable around joints, in areas where skin surfaces touch, and on the scalp or neck. The affected skin is usually darker than the surrounding skin. The thickened skin can harbor bacteria, frequently resulting in a characteristic odor.

EHK is classified into two subtypes: PS-type and NPS-type. Individuals with the PS-type exhibit significant thickening of the skin on the palms of the hands and soles of the feet (palmoplantar hyperkeratosis), in addition to hyperkeratosis on other body areas. Those with the NPS-type have hyperkeratosis in regions other than the palms and soles, lacking the extensive palmoplantar involvement.

EHK belongs to a larger group of disorders known as ichthyoses, characterized by scaly skin. However, unlike some other ichthyoses, the skin in EHK is primarily thickened, not scaly.

Inheritance:

The inheritance of EHK can vary. Approximately 50% of EHK cases arise from spontaneous new mutations in the KRT1 or KRT10 gene, occurring in individuals without a family history of the condition. When EHK is inherited, it typically follows an autosomal dominant pattern. This means that inheriting only one copy of the mutated KRT1 or KRT10 gene is enough to cause the disorder. In rare instances, EHK resulting from KRT10 gene mutations can be inherited in an autosomal recessive manner. In this pattern, both copies of the gene must be mutated for the condition to manifest. Parents of individuals with autosomal recessive EHK each carry one copy of the mutated gene but usually do not exhibit any symptoms of the disorder themselves.