Erythrocyte reference values in Emirati people with and without α+ thalassemia

We studied the erythroid lineage in 1,079 citizens of United Arab Emirates (UAE). Subjects with abnormal hemoglobin (39), iron deficiency (136) or erroneous entries (8) were excluded. MCV distribution in the remaining individuals (896) was visibly bimodal. Statistical mixture analysis with Normix program was used to separate subpopulations with normal and small red cells. Hardy-Weinberg equation was used to estimate genotype frequencies.MCV of 78.0 fl separated phenotype-derived normal homozygotes (715) from phenotype-derived α+ thalassemia homozygotes (181). The erythrocyte indices were significantly different between the two groups (p < 0.0001). The overall prevalence of phenotype-derived α+ thalassemia homozygotes (-α/-α) was 0.20 and markedly varied among tribes, 0 to 0.31 (Mean = 0.15). The frequency of phenotype-derived α+ thalassemia allele was 0.44; when accounting for tribal population structure and inbreeding, the calculated frequency was 0.34. These values were very similar to those found in the same population by genotyping and other phenotyping methods. The erythrocyte reference values for phenotype-derived normal homozygotes in Emiratis closely overlapped with those for Caucasians and normal homozygotes defined by genotyping. The reference values for phenotype-derived α+ thalassemia homozygotes in Emiratis also closely overlapped with those for α+ thalassemia homozygotes defined by genotyping.In populations with frequent α+ thalassemia mutations, two sets of erythrocyte reference values could be determined without genotyping.The prevalence of α+ thalassemia allele in Peninsular Arabs varies between 0.07 and 0.58 [1-5]. In UAE nationals, the frequency of α+ thalassemia allele is reported to be between 0.30 and 0.37 [1,2]. In these populations, the most common mutations are deletional, involving one of the linked pair of α-globin genes. Consequently, the genotypes are heterozygous α+ thalassemia (-α/αα), homozygous α+ thalassemia (-α/-α) and normal genot