描述
S-Adenosylhomocysteine (SAH) Hydrolase Deficiency (Hypermethioninemia, familial) results from AHCY gene defect. AHCY codes for S-adenosylhomocysteine hydrolase (SAH). SAH catalyzes the hydrolysis of S-adenosylhomocysteine to adenosine and homocysteine. S-adenosylhomocysteine is a byproduct of S-adenosylmethionine-dependent methyltransferases. This hydrolysis reaction is a common way to eliminate S-adenosylhomocysteine in eukaryotes. SAH Deficiency causes accumulation of guanidinoacetate, homocysteine, methionine, s-adenosylhomocysteine and s-adenosylmethionine in plasma, and methionine in spinal fluid. Symptoms include cerebral atrophy, dysmorphism, strabismus, jaundice, mental and motor retardation.