Studies on the molecular defect in galactosemia.

The galactose metabolic pathway and some of the consequences of deficient galactokinase or gal-1-P uridyltransferase activity have been discussed. The existence of CRM in transferase deficiency galactosemia is presented as evidence that this disease is the result of a structural gene mutation. The finding of both quantitative and qualitative variation in transferase CRM among different galactosemic patients argues that genetic heterogeneity exists within this group. Data supporting a Ping-Pong mechanism of action for human transferase reaction is proposed.