Aniridia (aniridia) - Gen PAX6
Aniridia is an ocular congenital malformation characterized by the total or partial absence of the iris. This alteration can present a spectrum of ocular manifestations including aniridia or foveal hypoplasia are the major manifestations. The involvement may be isolated, affecting only the iris, or associated with other panoculares anomalies with involvement of the cornea (opacity), angle of the anterior chamber (glaucoma), crystal (dislocation and / or cataracts), retina (foveal hypoplasia), macula and optic nerve (hypoplasia).
Genetic alteration of these patients lies in a mutation of PAX6 (Paired box 6) gene on short arm of chromosome 11 (11p13). This gene encodes a transcription factor (protein PAX6), a protein that controls the early stages of ocular and cerebral morphogenesis. It is believed that this protein activates genes involved in the formation of the eyes, central nervous system and pancreas. The gene of 22 kb, possesses 14 exons and 13 introns, encoding a polypeptide of 422 amino acids with two DNA binding domains, one domain bipartite a couplet, and the other a couplet domain homogeneous. The first is encoded by exons 5 and 7 and has in turn two subdomains, one relatively conserved 74 amino acid at the NH 2 -terminal, and a more divergent 34 amino acid at the carboxy terminus. The latter is where mutations of which have been found up to 500, and involve the synthesis of a truncated protein occur more frequently. Nonsense mutations (nonsense) result aniridia, and mutations loss sense (misssense) are related foveal hypoplasia, congenital cataract or disorders of the ocular anterior chamber.
Aniridia is inherited as an autosomal dominant, which means that a copy of the altered gene in each cell is sufficient to express the disease. In about two thirds of cases, an affected person inherits the mutation from an affected parent. The remaining third of cases are due to 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 aniridia, by complete PCR amplification of exons PAX6, and subsequent sequencing. We recommend starting the study by those exons which have been described more frequently mutations, and where to find them , just studying the other exons when required.
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).