Corneal dystrophy type I (Lattice corneal dystrophy type I) - Gen TGFBI.

Corneal dystrophy type I is an eye disorder that affects the cornea. This disease is characterized by the accumulation in the stromal layer of the cornea, of lumps of proteins known as amyloid deposits, causing a deterioration in vision. Often, affected individuals have recurrent corneal erosions, which are caused by the separation of the individual layers of the cornea each other. These corneal erosions are very painful and can cause photophobia. Corneal dystrophy type I manifests in childhood or adolescence and leads to vision problems in early adulthood.

This process is due to mutations in the TGFBI, located on the long arm of chromosome 5 (5q31). This gene encodes a beta-induced, found in many body tissues, including corneal protein called transforming growth factor. The TGFBI protein is part of the extracellular matrix. It is believed that this protein plays a role in cell adhesion and migration.

They have identified at least 26 mutations in the TGFBI in people with corneal dystrophy type I gene mutation changing amino acids in the protein TGFBI, causing the altered proteins are grouped abnormally and form amyloid deposits. The most common mutation replaces the amino acid arginine to the amino acid cysteine at position 124 (R124C or Arg124Cys). It is unclear how mutations in the gene induce the protein to form deposits.

This disease is inherited as an autosomal dominant, which means that a copy of the altered gene in each cell is sufficient for alteration may be expressed. In most cases, an affected person has a parent with the disorder.

Tests performed in IVAMI: in IVAMI perform detection of mutations associated with corneal dystrophy type I, by complete PCR amplification of exons TGFBI, 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).