hematology and oncology
Glucose 6 Phosphate Dehydrogenase (G6PD) Deficiency
Introduction
Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X-linked enzymatic defect common in people with African ancestry that can result in hemolysis after acute illnesses or intake of oxidant drugs (including salicylates and sulfonamides). Diagnosis is based on assay for G6PD, although test results are often falsely negative during acute hemolysis due to the presence of reticulocytes, which are richer in G6PD than older cells. Treatment is supportive. (See also Overview of Hemolytic Anemia .) G6PD deficiency, a defect in the hexose monophosphate shunt pathway, is the most common disorder of red blood cell (RBC) metabolism. The G6PD gene is located on the X chromosome and exhibits a high amount of variation (polymorphism), resulting in a range of G6PD activity from normal to severely deficient. Variants are classified I through V by the amount of activity of the G6PD enzyme. Because the gene is X-linked, males are more likely to present with clinically significant hemolysis. Females who are homozygous, or who are heterozygous with skewed X inactivation that results in a high proportion of affected X chromosomes may also be affected. In the US, this defect is most common in people with African ancestry, occurring in about 10% of male African Americans and in<10% of female African Americans. It occurs in lower frequencies among people from the Mediterranean basin (eg, Italian, Greek, Arab, or Sephardic Jewish ancestry) and people with Asian ancestry. 