Residual adenylosuccinase activities in fibroblasts of adenylosuccinase-deficient children: parallel deficiency with adenylosuccinate and succinyl-AICAR in profoundly retarded patients and non-parallel deficiency in a mildly retarded girl - Van den Bergh, F; Vincent, M F; Jaeken, J; Van den Berghe, G (J Inherit Metab Dis, 1993)