THE FREQUENCY OF GLUCOSE-6-PHOSPHATE-DEHYDROGENASE PHENOTYPES AND SICKLE-CELL GENES IN AL-QATIF OASIS

This study was conducted on a selected population of Al-Qatif in Easte rn Saudi Arabia to determine the gene frequencies of glucose-6-phospha te dehydrogenase (G-6-PD) deficiency and sickle cell (HbS) genes and t o study the extent of interaction between the two genes. A total of 96 0 blood samples collected from Saudi males (515) and females (445) att ending the outpatient clinics and hospitals for minor illnesses were s ubjected to electrophoresis for separation of hemoglobin types and G-6 -PD phenotyping and for spectrophotometric determination of G-6-PD act ivity. The prevalence of HbS heterozygotes was 25.9%, Hb S/beta-degree -thalassemia was 1.563% and HbS homozygotes was 2.917%. The overall ge ne frequency of HbS was 0.1666. Severe glucose-6-phosphate dehydrogena se deficiency was encountered in a large percentage of the population with a frequency of 0.392 for G-6-PD Mediterranean and 0.0058 for G-6- PD-A- in the male population and 0.2020 and 0.0112 for G-6-PD Mediterr anean and G-6-PD-A- in the female population respectively. Partial def iciency was encountered at a frequency of 0.0272 and 0.0697 in the mal e and female population respectively. G-6-PD deficiency caused by G-6- PD Mediterranean occurred at a higher frequency in individuals with no rmal hemoglobin (Hb AA) (0.414 and 0.217 in males and females respecti vely) compared to the HbS heterozygotes (0.338 and 0.168 in males and females respectively) and HbS homozygotes and HbS beta(o)-thalassemia cases (0.3125 and 0.1852 in males and females respectively). Compared to all areas of Saudi Arabia, Al-Qatif had the highest gene frequencie s for HbS and G-6-PD deficiency genes.