Multiple steatocystoma (steatocystoma multiplex) - Gen KRT17  

Multiple steatocystoma, also known as sebocistomatosis (sebocystomatosis) is a skin disorder characterized by the development of multiple benign cysts known as steatocystomas. These cysts are initiated in the sebaceous glands of the skin that are filled with grease. In affected individuals, the steatocystomas usually first appear during adolescence and are most often found on the back, neck, arms and thighs. In most of those affected, these cysts are the only sign of the disease. However, some affected individuals also have mild abnormalities affecting the teeth or fingernails and toenails.

This process is due to mutations in the gene KRT17 (Keratin 17), located on the long arm of chromosome 17 (17q21.2). This gene encodes keratin 17 or K17. Keratins are a group of tough fibrous proteins that form the structural framework of certain cells, particularly in cells that make up the skin, hair, nails, and the like tissues. Keratin 17 is encoded in nails, hair follicles and skin of the palms and soles of the feet. It is also found in the sebaceous glands of the skin that produce sebum which lubricates the skin and hair. Keratin 17 binds with similar protein, keratin 6b, to form keratin intermediate filaments. These filaments are assembled in dense networks that provide strength and resistance to skin, nails and other tissues. Networks keratin filaments protect these tissues from damage from friction and other daily physical stresses. In addition, this protein is also involved in wound healing.

They have identified at least four mutations in the gene responsible for Multiple KRT17 steatocystoma. It is believed that this alteration may be a mild form of congenital pachyonychia. Genetic mutations responsible for this process KRT17 change individual amino acids in the protein keratin 17, which interferes with the overall network of keratin intermediate filaments. In the sebaceous glands, these anomalies keratin lead to the development of steatocystomas. It is unclear why these cysts containing sebum often the only characteristic of the disease.

When the disease is due to mutations in the gene KRT17, it is inherited as an autosomal dominant pattern. Autosomal dominant inheritance means that a copy of the altered gene in each cell is sufficient to express the disease. In most cases, an affected person inherits the disease from an affected parent. In people with multiple steatocystoma who have identified genetic mutations KRT17, usually no family history of the disease.

Tests in IVAMI: in IVAMI perform detection of mutations associated with multiple steatocystoma, by complete PCR amplification of the exons of the gene KRT17, 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).