Red blood cell indices and prevalence of hemoglobinopathies and glucose 6 phosphate dehydrogenase deficiencies in male Tanzanian residents of Dar es Salaam

Abstract

Hemoglobinopathies, disorders of hemoglobin structure and production, are one of the most common monogenic disorders in humans. Glucose 6 phosphate dehydrogenase deficiency (G6PD) is an inherited enzymopathy resulting in increased oxygen stress susceptibility of red blood cells. The distributions of these genetic traits in populations living in tropical and subtropical regions where malaria has been or is still present are thought to result from survival advantage against severe life threatening malaria disease. 384 male Tanzanian volunteers residing in Dar es Salaam were typed for G6PD, sickle cell disease and α-thalassemia. The most prominent red blood cell polymorphism was heterozygous α(+)-thalassemia (37.8%), followed by the G6PD(A) deficiency (16.4%), heterozygous sickle cell trait (15.9%), G6PD(A-) deficiency (13.5%) and homozygous α(+)-thalassemia (5.2%). 35%, 45%, 17% and 3% of these volunteers were carriers of wild type gene loci, one, two or three of these hemoglobinopathies, respectively. We find that using a cut off value of 28.6 pg. for mean corpuscular hemoglobin (MCH), heterozygous α(+)-thalassemia can be predicted with a sensitivity of 84% and specificity of 72% in this male population. All subjects carrying homozygous α(+)-thalassemia were identified based on their MCH value < 28.6 pg.

Keywords: Sickle cell trait; Tanzania; glucose 6 phosphate dehydrogenase deficiency; malaria; mean corpuscular hemoglobin; screening; whole blood count; α-thalassemia.

Figure 1

Box plots for RBC indices. Box plots representing the mean and lower and upper quartiles for RBC count (A), Hemoglobin (B), HKT (C), MCV (D), MCH (E) and MCHC (F) in the groups of volunteers expressing one particular RBC polymorphism given on the x-axis. Statistically significant deviations from values obtained in the wild type population are marked (*).

Figure 2

ROC analysis for MHC values within the α⁺-thalassemia population. ROC analysis for MCH defining 28.6 pg. as a suitable value for identification of heterozygous and homozygous male α⁺-thalassemia carriers.