ENZYMATIC AND IMMUNOLOGICAL DEMONSTRATION OF NORMAL AND DEFECTIVE SUCCINIC SEMIALDEHYDE DEHYDROGENASE-ACTIVITY IN FETAL BRAIN, LIVER AND KIDNEY

Succinic semialdehyde dehydrogenase (SSADH; EC 1.2.1.24) deficiency (M cKusick 271980) is an inborn error of 4-aminobutyric acid (GABA) metab olism. The enzymatic defect blocks the oxidation of succinic semialdeh yde (SSA) to succinic acid, resulting in conversion of SSA to 4-hydrox ybutyric acid (gamma-hydroxybutyric acid, GHB), which accumulates in p atients' physiological fluids. SSADH-deficient patients present with v ariable retardation of intellectual, motor and speech development, oft en accompanied by ataxia and hypotonia (Jakobs et al 1993a). Prenatal diagnosis of SSADH deficiency, associated with elevated GHB in amnioti c fluid and deficient SSADH activity in cultured amniocytes, has been reported (Jakobs et al 1993b). The present communication extends these findings by reporting SSADH deficiency in affected fetal brain, liver and kidney, representing the first demonstration of SSADH deficiency in brain and SSADH expression in normal human liver and kidney.