G6PD

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a genetic condition that can result in the premature breakdown of red blood cells, leading to anaemia.

Men are at a higher risk of this deficiency than are women, as one altered copy of this gene on the X chromosome is enough to cause the condition. For women, a mutation would have to appear on both copies of the gene.

Other risk factors include a family history of G6PD deficiency and African-American or Mediterranean descent. However, a recent study done in an urban US clinic found that 10% of black female patients versus 15% of male patients (all races) had this disorder.¹

This would certainly be a consideration before initiating therapy for pneumocystis pneumonia (PCP). It is also a concern for young children who are being given cotrimoxazole therapy (dapsone 2mg/kg dosed once daily can be substituted). 

On a more positive note, G6PD deficiency is believed to have a protective effect against the acquisition of malaria. Researchers have found that the geographical distribution of G6PD correlates with a lower incidence of malaria.² This however may also result in an increased prevalence of G6PD deficiency than might ordinarily occur.³