G6PD deficiency: the genotype-phenotype association

Summary 

Deficiency of glucose-6-phosphate dehydrogenase is a very common X-linked genetic disorder though most deficient people are asymptomatic. A number of different G6PD variants have reached polymorphic frequencies in different parts of the world due to the relative protection they confer against malaria infection. People, usually males, with deficient alleles are susceptible to neonatal jaundice, and acute hemolytic anemia, usually during infection, after treatment with certain drugs or after eating fava beans. Very rarely de novo mutations can arise causing the more severe condition of chronic nonspherocytic hemolytic anemia. Altogether 160 different mutations have been described. The majority of mutations cause red cell enzyme deficiency by decreasing enzyme stability. The polymorphic mutations affect amino acid residues throughout the enzyme and decrease the stability of the enzyme in the red cell, possibly by disturbing protein folding. The severe mutations mostly affect residues at the dimer interface or those that interact with a structural NADP molecule that stabilizes the enzyme.

Keywords: Red cells, Enzyme stability, Structural NADP, Hemolytic anemia, Neonatal jaundice, Favism

• 1 R387C when accompanied by N126D gives rise to Mount Sinai
• 2 Also described as Lodi, Modena, Ferrara II, Athens-like and Mexico.
• 3 Also described as Maewo, Chinese-2 and Kalo
• 4 Also described as Fukushime
• 5 Also described as Nashville, Anaheim and Calgary