Glucose-6-phosphate dehydrogenase deficiency
From Wiki4CAM
G6PD deficiency or Glucose-6-phosphate dehydrogenase deficiency is the most common enzyme deficiency worldwide. It causes a spectrum of disease including neonatal hyperbilirubinemia, acute hemolysis, and chronic hemolysis. Persons with this condition also may be asymptomatic. It is a X-linked inherited disorder. The condition most commonly affects persons of African, Asian, Mediterranean, or Middle-Eastern descent. it is estimated that approximately 400 million people are affected worldwide. Homozygotes and heterozygotes can be symptomatic, although the disease typically is more severe in persons who are homozygous for the deficiency. Different gene mutations cause different levels of enzyme deficiency, with classes assigned to various degrees of deficiency and disease manifestation. Because acute hemolysis is caused by exposure to an oxidative stressor in the form of an infection, oxidative drug, or fava beans, treatment is geared toward avoidance of these and other stressors. Acute hemolysis is self-limited, but in rare instances it can be severe enough to warrant a blood transfusion. Neonatal hyperbilirubinemia may require treatment with phototherapy or exchange transfusion to prevent kernicterus. The variant that causes chronic hemolysis is uncommon because it is related to sporadic gene mutation rather than the more common inherited gene mutation.
Pathophysiology
It is known that glucose-6-phosphate dehydrogenase catalyzes nicotinamide adenine dinucleotide phosphate (NADP) to its reduced form, NADPH, in the pentose phosphate pathway. NADPH protects cells from oxidative damage. Because erythrocytes do not generate NADPH in any other way, they are more susceptible than other cells to destruction from oxidative stress. The level of G6PD activity in affected erythrocytes generally is lower than in other cells. Normal red blood cells that are not under oxidative stress generally exhibit G6PD activity at approximately 2 percent of total capacity. Even with enzyme activity that is substantially reduced, there may be few or no clinical symptoms. A total deficiency of G6PD is incompatible with life. The G6PD-deficient variants are grouped into different classes corresponding with disease severity
Exams and tests
The conversion of nicotinamide adenine dinucleotide phosphate to its reduced form in erythrocytes is the basis of diagnostic testing for the deficiency. This usually is done by fluorescent spot test.
