Genetic control of the proportion of gamma chains of human fetal haemoglobin.
The relative proportions of gamma chains of human fetal haemoglobin G gamma, A gamma 75 Ileu (A gamma I) and A gamma 75 Thr (A gamma T) were investigated in homogeneous populations of patients in Algeria exhibiting sickle cell disease and in patients in Algeria and Sardinia with beta-thalassaemia. The restriction site haplotypes within the beta gene cluster were known. The results suggest a tight genetic regulation of the G gamma/A gamma + G gamma ratio (G gamma ratio) which is associated with the G gamma Hind III site of polymorphism (p less than 0.0001). From the present results and those in the literature the high G gamma ratio is associated with the presence of 3 polymorphic restriction sites: Xmn1 5' to the G gamma gene, Hind III in the G gamma IVS II and Hinc II in the psi beta gene. Familial studies showed that the expression of the A gamma alleles is genetically determined. The wide variation of the A gamma T/A gamma T + A gamma I ratio (A gamma ratio) between families is most probably related to the various haplotypes bearing the A gamma I alleles.
D000462:Algeria; D000483:Alleles; D000755:Anemia, Sickle Cell / Q000235:genetics; D005319:Fetal Hemoglobin / Q000235:genetics*; D005838:Genotype; D006239:Haplotypes; D006720:Homozygote; D006801:Humans; D007558:Italy; D011110:Polymorphism, Genetic; D013789:Thalassemia / Q000235:genetics
D005319:Fetal Hemoglobin