G6PD(Glucose-6-phosphate 1-dehydrogenase) belongs to the glucose-6-phosphate dehydrogenase family. It is a housekeeping enzyme encoded in mammals by an X-linked gene. G6PD has important functions in intermediary metabolism because it catalyzes the first step in the pentose phosphate pathway and provides reductive potential in the form of NADPH.. This protein has 3 isoforms produced by alternative splicing.