What causes glucose-6-phosphate dehydrogenase (G6PD) deficiency?

Updated: Jun 25, 2020
  • Author: Lawrence C Wolfe, MD; Chief Editor: George T Griffing, MD  more...
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Answer

G6PD deficiency is an X-linked recessive enzymopathy caused by a missense mutation in the housekeeping G6PD gene. [13] The pattern of inheritance is similar to that of hemophilia and color blindness: males usually manifest the abnormality and females are carriers. Females can be symptomatic if they are homozygous or if their normal X chromosome is inactivated.

The G6PD gene is located in the distal long arm of the X chromosome at the Xq28 locus. More than 160 mutations in the G6PD gene (OMIM #305900) have been reported. [13] Most are single-base changes that result in an amino acid substitution. These substitutions affect enzyme activity by decreasing intracellular stability of the protein or by affecting their catalytic activity. [14, 15, 16]

A large deletion in the G6PD gene is incompatible with life. Although small deletion mutation is rare, it has been reported and presents with severe G6PD deficiency. [16]

Specific G6PD alleles are associated with G6PD variants with different enzyme levels and, thus, different degrees of clinical disease severity. The variation in G6PD levels accounts for differences in sensitivity to oxidants.

The most common G6PD variants includes G6PD A-, G6PD Mediterranean, G6PD Canton, and G6PD Union. [16]


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