Glucose-6-phosphate-dehydrogenase (G6PD) deficiency is an inherited disease that can cause anemia, or a low red blood cell count.
G6PD deficiency occurs when a person doesn't have enough of an enzyme called glucose-6-phosphate-dehydrogenase. This enzyme is important in metabolism. Red blood cells, which carry oxygen, don't get enough energy when G6PD is lacking. The red blood cells die too soon in this condition, which can cause anemia. Anemia can be mild or severe and is often triggered suddenly by illness, foods, or certain medications.
G6PD deficiency is inherited on the X chromosome. The X chromosome helps determine whether a person will be male or female. This disease is therefore called "sex-linked" and usually only occurs in men. This is because men only need to inherit one abnormal gene to get the disease. Women, on the other hand, have to inherit two abnormal genes to get the disease. In the US, a mild form of G6PD deficiency is very common in blacks. Those from the eastern Mediterranean region are at a higher risk for a more severe form of G6PD deficiency.
Sudden attacks of G6PD deficiency, or a hemolytic crisis, can be caused by: