Vohwinkel syndrome ...- (Vohwinkel syndrome) - Gen GJB2 (connexin 26).
Vohwinkel syndrome is a disorder that affects the skin, with classical forms and variants. In the classic form of Vohwinkel syndrome, affected individuals have thickened epidermal thickness honeycomb on the palms of hands and soles of the feet (palmoplantar keratosis) that begin in infancy or early childhood. Children usually also have areas of thickened skin in the form of starfish on the tips of the fingers and toes, or knees. A few years, narrow bands of abnormal fibrous tissue around his fingers and toes (pseudoainhum), which can prevent the movement of the fingers and lead to spontaneous amputations develop. People with the classic form of the disease also have hearing loss.
The variant form of Vohwinkel syndrome does not involve hearing loss. Those affected have dry, scaly skin (ichthyosis), especially in the extremities. Ichthyosis is usually mild, and may also have slight reddening of the skin (erythrodermic). Some affected infants are born with a transparent coating that covers your skin, called collodion membrane, which is usually lost during the first weeks of life.
This process is due to mutations in the GJB2, located in the long arm of chromosome 13 (13q11-q12), encoding Gap-beta-2 protein, known as connexin-26. Connexin-26 form channels that allow the transport of nutrients, ions, and signaling molecules between cells.
Connexin-26 is found in cells throughout the body, including the inner ear and skin. In the inner ear, connexin channels 26 are in the cochlea. These channels can help maintain the proper concentration of potassium ions required for converting sound waves into electrical nerve impulses. This conversion is essential for normal hearing. Moreover, connexin-26 may be involved in the maturation of certain cells of the cochlea. Connexin-26 also plays a role in the growth, maturation and stability of the epidermis.
They have identified at least three GJB2 gene mutations in persons with Vohwinkel syndrome. These mutations alter connexin-26 by interrupting its function in normal cells and may interfere with the function of other connexin proteins.
This condition is inherited as an autosomal dominant, which means that a copy of the altered gene in each cell is sufficient to cause the disorder. In most cases, an affected person inherits the mutation from an affected parent. Other cases result from new mutations in the gene and occur in people with no history of disease in your family.
Tests in IVAMI: in IVAMI perform detection of mutations associated with Vohwinkel syndrome, by complete PCR amplification of exons GJB2, 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).