Frequencies of glucose 6-phosphate dehydrogenase pyruvate kinase and hexokinase deficiencies in the Basrah population of Iraq

Abstract

Introduction: The frequencies of enzyme deficiencies that cause hemolytic anemia among Iraqi people in southern Iraq have been studied. These hereditary red blood cell enzymes include glucose 6-phosphate dehydrogenase (G6PD), pyruvate kinase (PK) and hexokinase (HK). The most common enzyme deficiency is G6PD deficiency, an X-linked recessive trait. PK deficiency is associated with chronic hemolytic anemia, but HK deficiency is a rare autosomal recessive enzymopathy. Methods: A total of 1497 clinically normal neonates and 1629 apparently healthy adults from Iraqi Arab original inhabitants of Basrah were studied. Blood samples obtained from the umbilical cord of the newborns or by venipuncture from adults were collected in ACD anticoagulant and stored at 4 °C. Erythrocyte G6PD activity was measured qualitatively by the fluorescent spot test or methemoglobin reduction test and confirmed quantitatively by spectrophotometric analysis. PK and HK activities were estimated only quantitatively by spectrophotometry. Results: Only seven partially deficient infants out of 506 infants and 343 adults were detected with PK deficiency. On this basis, the incidence would be 0.82 with an estimated gene frequency of about 0.004. Partial HK deficiency was found in only one female infant out of 220 infants and 246 adults in both sexes. No case of complete deficiency of these enzymes was identified. G6PD deficiency was identified in 131 out of 1040 male infants and adults. All the affected males seemed to have severe deficiency (hemizygotes). On this basis, we estimated the gene frequency to be about 12.6%. In the female population, 31 out of 771 female infants and adults had severe enzyme deficiency, a frequency of 4.0% (possible homozygosity) while 67 females showed intermediate or moderate enzyme activity (heterozygosity), a prevalence of 8.7%. Discussion: Among the Iraqi Arab populations that are original inhabitants of Basrah, erythrocytes G6PD deficiency is by far the most common enzyme deficiency that causes hemolytic anemia. The gene frequencies for male infants and adults were 11.7% and 13.1%, respectively. The observed female incidences, for both infants and adults, were far from those expected. Factors that might be the causes of such discrepancies were discussed.