Glutaric Aciduria Type 1 - Genetics

Genetics

The condition is inherited in an autosomal recessive pattern: mutated copies of the gene GCDH must be provided by both parents to cause glutaric acidemia type 1. The GCDH gene encodes the enzyme glutaryl-CoA dehydrogenase. This enzyme is involved in degrading the amino acids lysine, hydroxylysine and tryptophan. Mutations in the GCDH' gene prevent production of the enzyme or result in the production of a defective enzyme with very low residual activity, or an enzyme with relatively high residual activity but still phenotypic consequences. This enzyme deficiency allows glutaric acid, 3-hydroxyglutaric acid and (to a lesser extent) glutaconic acid to build up to abnormal levels, especially at times when the body is under stress. These intermediate breakdown products are particularly prone to affect the basal ganglia, causing many of the signs and symptoms of glutaric acidemia type 1.

Glutaric acidemia type 1 occurs in approximately 1 of every 30,000 to 40,000 births. It is much more common in the Amish community and in the Ojibway population of Canada, where up to 1 in 300 newborns may be affected.

Relatives of children with GA1 can have very low GCDH activity: in an early study of GA1, GCDH activity was found to be 38%, 42%, and 42% of controls in three of the four relatives tested. Those levels are close to those found by Christensen & al in some heavily symptomatic GA1-affected children.

This article incorporates public domain text from The U.S. National Library of Medicine