HETEROGENEITY OF GAMMA-GLOBIN CHAIN SYNTHESIS IN SAUDI NEWBORNS

Cord blood samples from 655 unselected neonates born to Saudi mothers at King Fahad National Guard Hospital, Riyadh, Saudi Arabia were analysed to determine the levels of gamma-globin chains in Saudis. The percentage of three types of gamma-chains of human fetal hemoglobin (A-gamma-T, G-gamma and A-gamma-I) was obtained by high-performance liquid chromatographic (HPLC) method. Although the majority of babies (631/655) had normal G-gamma values in the range of 58-74%, there were only 69% with normal G-gamma/A-gamma ratio (Table 1). The A-gamma-T chain or HbF Sardinia was present in 28% of the total neonates with a gene frequency of 0.160. The A-gamma-T values in this group ranged between 11-42%. Eight babies (1.2%) had G-gamma levels 45% or less (mean 41 +/- 3%) and in 16 neonates (2.4%), G-gamma values were highly elevated (mean 81.4 +/- 2.8%). The frequency of two G-gamma-globin genes was 0.0061 and 0.0122, respectively, which is comparable with other ethnic or racial groups. The differences in G-gamma to A-gamma ratio in some Saudi babies could be due to an abnormal arrangement of gamma-globin genes of beta-globin gene cluster which is now being investigated.