Keratitis, ichthyosis and deafness syndrome ... (keratitis-ichthyosis-deafness syndrome) - Gen GJB2.
Syndrome keratitis, ichthyosis and deafness (KID) is characterized by eye problems, skin abnormalities and hearing loss. Usually, people with KID syndrome have keratitis, which can cause pain, photophobia, corneal neovascularization and scarring. Over time, affected individuals have decreased visual acuity. In severe cases of keratitis can lead to blindness. Other associated signs may include palmoplantar keratoderma, erythrokeratodermia and ichthyosis. Approximately 12% of affected people develop squamous cell carcinoma, which can also affect mucous membranes, such as the lining of the mouth. Partial hair loss is a common feature of KID syndrome and often affects the eyebrows and eyelashes. In addition, hearing loss associated with this disease is usually deep, but sometimes it is less severe.
This process is due to mutations in the GJB2, located in the long arm of chromosome 13 (13q11-q12). This gene encodes the protein beta-2 Gap junction, known as connexin 26. The connexin 26 channels so as to allow the transport of nutrients, ions and molecules of signaling between cells. Connexin 26 was found in cells throughout the body, including the inner ear and skin. In the inner ear, formed by connexin 26 channels they are in the cochlea. These channels can help maintain the proper level 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 been identified at least 9 mutations GJB2 in people with keratitis, ichthyosis and deafness (KID) syndrome, the most frequent mutation D50N. These genetic changes replace individual amino acids in the connexin 26, leading to constantly escape channels that let ions, which harms the health of cells and increases cell death. Death of cells in the skin and inner ear can be the basis of ichthyosis and deafness syndrome occurring in KID. It is unclear how the GJB2 gene mutations affecting the eyes.
The KID syndrome is usually inherited in an autosomal dominant pattern, which means that a copy of the altered gene in each cell is sufficient to express the disease. In some cases, an affected person inherits the mutation from an affected parent. However, most cases are due to new mutations in the gene and occur in people with no history of disease in your family. Some families have had a similar alteration KID syndrome with autosomal recessive inheritance pattern. In the autosomal recessive both gene copies in each 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. Affected individuals in these families have liver disease, which is not a feature of the autosomal dominant form. The autosomal recessive form is sometimes referred to Desmons syndrome. It is not known if it is due to mutations GJB2.
Tests in IVAMI: in IVAMI perform detection of mutations associated with keratitis, ichthyosis and deafness (KID) 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).