G6PD Deficiency and Oxidative Stress: Gene Function, Disease Mechanisms, and Clinically Relevant Variants
What is G6PD? An Overview of the Gene, Enzyme, and Oxidative Stress Pathway Glucose-6-phosphate dehydrogenase (G6PD) is a critical metabolic enzyme encoded by the G6PD gene. It functions as the first and rate-limiting enzyme in the pentose phosphate pathway (PPP), a metabolic route that serves as a central hub for cellular antioxidant defense and nucleotide synthesis. G6PD catalyzes the oxidation of glucose-6-phosphate, generating two essential products: NADPH, the primary source of reducing power for cellular redox balance, and ribose-5-phosphate, a key precursor for nucleotide biosynthesis. NADPH is indispensable for regenerating reduced glutathione (GSH), which directly determines a cell’s ability to neutralize oxidative stress. Consequently, proper G6PD activity is essential for maintaining erythrocyte integrity and supports the unique metabolic demands of tumor cells. The G6PD gene is located on the X chromosome (Xq28). More than 230 point mutations have been identified, and appro...