Glucose-6-Phosphate Dehydrogenase (G6PD) deficiency is the most common human enzyme deficiency; an estimated 400 million people worldwide are affected . G6PD deficiency is an X-linked condition that causes destruction of red blood cells. G6PD is in the hexose monophosphate pathway, the only NADPH-generation process in mature red blood cells, which lack the citric acid cycle. Deficiency of G6PD, in various forms, is the basis of favism, primaquine sensitivity and some other drug-sensitive hemolytic anemias, anemia and jaundice in the newborn, and chronic hemolytic anemia. Symptoms of a hemolytic crisis can include dark urine, an enlarged spleen, fatigue, paleness, shortness of breath, rapid heart rate, and jaundice. Severe hemolytic crisis can produce hemoglobinuria. Laboratory tests may reveal an elevated absolute reticulocyte count, elevated bilirubin levels, elevated serum LDH, low red blood cell count, and low hemoglobin levels. Transfusions may occasionally be needed. Spontaneous recovery from hemolytic crises is the usual outcome, although kidney failure or death may occur following a severe hemolytic event.
Different variants of the enzyme are found in high frequency in African, Mediterranean, and Asiatic populations . Heterozygote advantage from malaria has been proposed to account for the high frequency of the particular alleles in particular populations . The G6PD (Xq28) variants have been divided into 5 classes according to the level of enzyme activity. These are: class 1--enzyme deficiency with chronic hemolytic anemia; class 2--severe enzyme deficiency (less than 10%); class 3--moderate to mild enzyme deficiency (10-60%); class 4--very mild or no enzyme deficiency (60%); class 5--increased enzyme activity.
- 1. Scriver et al. "Glucose-6-Phosphate Dehydrogenase Deficiency." In: The metabolic and molecular bases of inherited disease. 1995. 7th ed. n.p.: McGraw- Hill, Inc.:3367-98.
- 2. Porter et al. Variation of glucose-6-phosphate dehydrogenase in different populations. Lancet 1964, I:895-899.
- 3. Luzzatto et al. Glucose-6-phosphate dehydrogenase deficient red cells: resistance to infection by malarial parasites. Science 1969, 164:839-842.
- 4. Noori-Daloii et al. A comprehensive study on the major mutations in glucose-6-phosphate dehydrogenase-deficient polymorphic variants identified in the coastal provinces of Caspian Sea in the north of Iran. Clin. Biochem. 2007, 40:699-704.
- 5. Laosombat et al. Molecular heterogeneity of glucose-6-phosphate dehydrogenase (G6PD) variants in the south of Thailand and identification of a novel variant (G6PD Songklanagarind). Blood Cells Mol. Dis. 2005, 34:191-196.
- Confirmation of a clinical/biochemical diagnosis of G6PD deficiency
- Carrier testing in females/adults with a family history of G6PD deficiency
Analytical Sensitivity: ~99%
Isolation using the Perkin Elmer™Chemagen™ Chemagen™ Automated Extraction method or Qiagen™ Puregene kit for DNA extraction is recommended.
Infants and Young Children (<2 years of age): 2-3 ml
Children > 2 years of age to 10 years old: 3-5 ml
Older Children & Adults: 5-10 ml
Autopsy: 2-3 ml unclotted cord or cardiac blood
Orangene™ Saliva Collection Kit used according to manufacturer instructions. Please contact EGL for a Saliva Collection Kit for patients that cannot provide a blood sample.
- Custom Diagnostic Mutation Analysis (KM) is available to family members if mutations are identified by sequencing.
- Prenatal testing is available for known familial mutations only. Please call the Laboratory Genetic Counselor before collecting a fetal sample.