Gyrate atrophy of the choroid and retina : Lymphocyte ornithine-δ-aminotransferase activity in different mutations and carriers

Deficiency of omithine-delta-aminotransferase (OAT) causes gyrate atrophy of the choroid and retina with hyperornithinemia (GA; McKusick 258870), a progressive autosomal recessive chorioretinal degeneration leading to early blindness. As residual enzyme activity may vary in different mutations of the OAT gene and explain individual variations in disease progression, a sensitive HPLC modification of the OAT assay in lymphocytes was developed, based on measurement of the dihydroquinozolinium reaction product. The OAT activities (ranges) of 43 Finnish GA patients with mutations L402P/L402P, R180T/L402P, N89K/ L402P, and L402P/x (x = previously unknown allele), were