Demonstration of 4-aminobutyric acid aminotransferase deficiency in lymphocytes and lymphoblasts.
Lysates of lymphocytes, isolated from whole blood, and Epstein-Barr virus transformed cultured lymphoblasts catalysed the transamination of 4-aminobutyric acid with 2-oxoglutaric acid as co-substrate. 4-Aminobutyric acid aminotransferase activity in lymphocyte and lymphoblast sonicates derived from 12 unrelated control individuals (6 each) was 39 +/- 19 pmol min(-1) (mg protein (-1] (mean +/- 1 SD). Activities in lysates of both types of cell derived from a Flemish patient were less than 3% of control. 4-Aminobutyric acid aminotransferase activity in sonicates derived from the parents and a healthy sibling were 15-37% of the control mean for lymphocytes and 13-20% of the control mean in lymphoblasts, respectively. Km values in a control lymphoblast sonicate were 0.63 and 0.08 mmol L(-1) for 4-aminobutyric and 2-oxoglutaric acids, respectively. These data indicate that the parents and healthy sibling are heterozygous and the patient is homozygous for a defective gene responsible for 4-aminobutyric acid aminotransferase deficiency, and that inheritance is autosomal recessive.
D000612:4-Aminobutyrate Transaminase / Q000097:blood / Q000172:deficiency* / Q000235:genetics; D000445:Aldehyde Oxidoreductases / Q000097:blood / Q000378:metabolism; D001792:Blood Platelets / Q000201:enzymology; D001921:Brain / Q000201:enzymology; D002478:Cells, Cultured; D005260:Female; D005808:Genes, Recessive; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D008214:Lymphocytes / Q000201:enzymology*; D008297:Male; D050644:Succinate-Semialdehyde Dehydrogenase
D000445:Aldehyde Oxidoreductases; C493643:ALDH5A1 protein, human; D050644:Succinate-Semialdehyde Dehydrogenase; D000612:4-Aminobutyrate Transaminase