Glucose-6-phosphate dehydrogenase d...

Glucose-6-phosphate dehydrogenase deficiency, the greatest in number common enzyme deficiency worldwide, causes a representation of disease including neonatal hyperbilirubinemia, acute hemolysis, and chronic hemolysis. living bodys with this condition also may be asymptomatic. This X-linked inherited disorder in the greatest degree commonly affects persons of African, Asian, Mediterranean, or Middle-Eastern journey [i]or[/i] voyage down Approximately 400 million people are affected worldwide. Homozygote and heterozygotes can be symptomatic, although the disease typically is more censorious in persons who are homozygous for the deficiency. The conversion of nicotinamide adenine dinucleotide phosphate to its reduc form in erythrocyte is the basis of diagnostic testing for the deficiency. This usually is done by the agency of fluorescent spot test. Different gene mutations cause different on a levels of enzyme deficiency, with classes assigned to various extents of deficiency and disease manifestation. Because acute hemolysis is caused by means of exposure to an oxidative stressor in the form of an infection, oxidative put drugs into or fava beans, treatment is geared toward avoidance of these and other stressors. Acute hemolysis is self-limited, if it were not that in rare instances it can be harsh enough to warrant a kin transfusion. Neonatal hyperbilirubinemia may require treatment with phototherapy or exchange transfusion to stop kernicterus. The variant that causes chronic hemolysis is extraordinary because it is related to sporadic gene mutation rather than the more public inherited gene mutation.

**********

Glucose-6-phosphate dehydrogenase (G6PD) deficiency increases the vulnerability of erythrocyte to oxidative stres Clinical presentations include acute hemolytic anemia, chronic hemolytic anemia, neonatal hyperbilirubinemia, and an absence of clinical symptoms. The disease is rarely fatal.

Epidemiology

G6PD deficiency appears with increased frequency throughout Africa, Asia, the Mediterranean, and the Middle East. In the United States, black males are chiefly commonly affected, with a prevalence of approximately 10 percent Prevalence of the deficiency is correlated with the geographic distribution of malaria, which has l to the theory that carriers of G6PD deficiency may incur partial protection against malarial infection. (1-3) Cases of sporadic gene mutation take place in all populations.

Pathophysiology

G6PD catalyzes nicotinamide adenine dinucleotide phosphate (NADP) to its reduc form, NADPH, in the pentose phosphate pathway (Figure 1 (4)) NADPH countenances cells from oxidative damage. Because erythrocyte do not generate NADPH in any other way, (3) they are more susceptible than other confined apartments to destruction from oxidative stres The flat of G6PD activity in affected erythrocyte generally is lower than in other solitary abode; squalids (5) Normal red blood confined apartments that are not under oxidative stres generally exhibit G6PD activity at approximately 2 percent of total capacity. (1) level with enzyme activity that is substantially reduc there may be not many or no clinical symptoms. A total deficiency of G6PD is incompatible with life. (6) The G6PD-deficient variants are form into groupsed into different classes corresponding with disease severity (Table 1 (17))

[FIGURE 1 OMITTED]

Genetics

The gene mutations affecting encoding of G6PD are plant on the distal long arm of the X chromosome More than 400 mutations have been identified, most numerous being missense mutations. (6) greatest in quantity of the variants occur sporadically, although the G6PD Mediterranean and the G6PD A- variants offer with increased frequency in certain populations (Table 2 (367))

Diagnosis

The diagnosis of G6PD deficiency is made from a quantitative spectrophotometric analysis or, more commonly from a rapid fluorescent spot touchstone detecting the generation of NADPH from NADP. (7) The standard is positive if the offspring spot fails to fluoresce in a less degree than ultraviolet light. (8) In field research, where quick screening of a large number of patients is extremityed other tests have been used; however, they require definitive testing to confirm an abnormal rise (9,10) Tests based on polymerase chain reaction descry specific mutations and are used for population screening, family studies, or prenatal diagnosis. (6)

In patients with acute hemolysis, testing for G6PD deficiency may be falsely negative because older erythrocyte with a higher enzyme deficiency have been hemolyzed. Young erythrocyte and reticulocytes have normal or near-normal enzyme activity. female heterozygotes may be hard to diagnose because of X-chromosome mosaicism leading to a partial deficiency that will not be descryed reliably with screening tests. (71112)

G6PD deficiency is individual of a group of congenital hemolytic anemias, and its diagnosis should be considered in children with a family history of jaundice, anemia, splenomegaly, or cholelithiasis, especially in those of Mediterranean or African ancestry. (13)

Testing should be considered in children and adults (especially males of African, Mediterranean, or Asian descent) with an acute hemolytic reaction caused by dint of infection, exposure to a known oxidative put drugs into or ingestion of fava beans.