Palmoplantar keratoderma Epidermolytic (Epidermolytic palmoplantar keratoderma) - Genes KRT1 and KRT9.

Epidermolytic palmoplantar keratoderma (PPK) is an inherited dermatologic disorder characterized by an area of diffuse thickening of the epidermis on the entire surface of palms and soles, surrounded by erythematous margin. Some patients may have areas of skin engrosaminto on the joints of the proximal phalanges.

This alteration was classified in diffuse forms, focal and punctate pattern according to the present hyperkeratosis in the palms and soles. Diffuse alteration occurs at birth or shortly thereafter, and affects the entire palm and sole, with a well - defined contour erythematosus. The focal alteration is a late - onset form in which the focal hyperkeratotic lesions develop in response to mechanical trauma. An important distinguishing feature is the presence of lesions in other body sites, for example, oral and follicular hyperkeratosis.

This process is due to mutations in genes KRT1 and KRT9. The KRT1 gene, located on the long (q) arm of chromosome 12 (12q13.13), encoding the protein keratin-1. Keratins are a group of tough and fibrous proteins that form the structural framework of cells called keratinocytes found in skin, hair and nails. Keratin-1 occurs in epidermal keratinocytes, including the skin of the palms and soles. Keratin-1 is associated with other keratins, keratin-9, or keratin-10, to form keratin intermediate filaments. These filaments are assembled to form solid networks add strength and elasticity to the skin and protect it from damage caused by friction and other everyday physical stresses. Mutations in the gene KRT1, palmoplantar keratoderma related epidermolytic, cause epidermolysis, manifested as skin blisters. People affected by no Epidermolytic palmoplantar keratoderma, palmoplantar hyperkeratosis they have no evidence of epidermolysis. In palmoplantar keratoderma striated type 3, thickening of the skin on the palms and soles follow a specific pattern. The KRT9 gene, located on the long (q) arm of chromosome 17 (17q21.2), encoding the keratin-9, a chain of intermediate filaments expressed only in the epidermis of palms and soles. Mutations in this gene cause palmoplantar keratoderma also epidermolytic.

This disease is inherited as an autosomal dominant, which means that a copy of an altered gene in each cell is sufficient to cause the alteration. It is believed that the severe form of the disease is inherited in an autosomal recessive pattern, that is, both copies of the gene in every cell must have mutations for alteration is expressed. The parents of an individual with an autosomal recessive disease have a copy of the mutated gene, but usually show no signs and symptoms of the disease.  

Tests in IVAMI: in IVAMI perform detection of mutations associated with palmoplantar keratoderma epidermolytic, by complete PCR amplification of the exons of KRT1 and KRT9 genes, respectively, and subsequent sequencing.

Samples recommended: EDTA blood collected for separation of blood leukocytes, or impregnated sample card with dried blood (IVAMI may mail the card to deposit the blood sample).