Ornithine aminotransferase deficiency
is a genetic condition that involves the choroid (the thin coating of the eye) and retina. It is characterized by elevated levels of orthinine in the body. Symptoms include poor vision at night or in dim light and peripheral vision loss. Patients may have good central vision into middle-age, however, total blindness usually occurs between the ages of 40 and 60. This deficiency is caused by a change in a gene called ornithine ketoacid aminotransferase (OAT) and is inherited in an autosomal recessive fashion.
There are two different forms of ornithine aminotransferase deficiency; one that is responsive to vitamin B6 supplementation and one that is not. Patients who are responsive may be prescribed vitamin B6 supplements. Those who have the unresponsive form may be recommended to maintain a low protein diet. Recent studies have also investigated the benefit of increasing lysine intake. The intended goal of these diet modifications is to reduce plasma ornithine levels. Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.