500px<unk> -6-phosphate<unk>  <unk>  is an enzyme in the pentose phosphate pathway (see image, also known as the HMP shunt pathway).<unk>  converts<unk> -6-phosphate into<unk> -phosphoglucono-δ-lactone and is the rate-limiting enzyme of this metabolic pathway that supplies reducing energy to cells by maintaining the level of the reduced form of the co-enzyme nicotinamide adenine dinucleotide phosphate (NADPH). The NADPH in turn maintains the supply of reduced glutathione in the cells that is used to mop up free radicals that cause oxidative damage. The<unk>  / NADPH pathway is the only source of reduced glutathione in red blood cells (erythrocytes). The role of red cells as oxygen carriers puts them at substantial risk of damage from oxidizing free radicals except for the protective effect of<unk> /NADPH/glutathione. People with<unk>  deficiency are therefore at risk of hemolytic anemia in states of oxidative stress. Oxidative stress can result from infection and from chemical exposure to medication and certain foods. Broad beans, e.g., fava beans, contain high levels of vicine, divicine, convicine and isouramil, all of which create oxidants. When all remaining reduced glutathione is consumed, enzymes and other proteins (including hemoglobin) are subsequently damaged by the oxidants, leading to cross-bonding and protein deposition in the red cell membranes. Damaged red cells are phagocytosed and sequestered (taken out of circulation) in the spleen. The hemoglobin is metabolized to bilirubin (causing jaundice at high concentrations). The red cells rarely disintegrate in the circulation, so hemoglobin is rarely excreted directly by the kidney, but this can occur in severe cases, causing acute kidney injury. Deficiency of<unk>  in the alternative pathway causes the buildup of<unk>  and thus there is an increase of advanced glycation endproducts (AGE). The deficiency also reduces the amount of NADPH, which is required for the formation of nitric oxide (NO). The high prevalence of diabetes mellitus type 2 and hypertension in Afro-Caribbeans in the West could be directly related to the incidence of<unk>  deficiency in those populations. Although female carriers can have a mild form of<unk>  deficiency (dependent on the degree of inactivation of the unaffected X chromosome – see lyonization), homozygous females have been described; in these females there is co-incidence of a rare immune disorder termed chronic granulomatous disease (CGD).
Glucose-6-phosphate dehydrogenase deficiency
Pyruvate kinase deficiency
Ribose-5-phosphate isomerase deficiency
Hereditary spherocytosis
Glutaminase deficiency
Sickle cell disease
6-phosphogluconate dehydrogenase deficiency
Aldolase A deficiency