Although G6PD deficiency, which can cause problems in red blood cells upon certain triggers, is the most common human enzyme defect, affecting over 400 million people, including over 1 in 10 Black Case report: Metformin induced hemolytic anemia in a glucose 6 phosphate dehydrogenasedeficient patient Alaa M Salamat, Hani M Ammar, Ahmed I Alsagheir, Hayat S Mushcab, 2025 PeerJ The research progress on the role of glucose 6 phosphate dehydrogenase in immune regulation Glucose 6 phosphate dehydrogenase (G6PD) deficiency X linked recessive Xq28 is not true recessive as heterozygotes can express the trait; G6PD > No NADPH > No RBC glutathione protection > free radical damage hemolysis