Prevalence of thalassaemias in ethnic Saudi Arabians.

A study of the prevalence of alpha- and beta-thalassaemia and the sickle cell gene was carried out on 840 healthy adult male Saudi Arabians of different tribal origins. Complete blood count, haemoglobin electrophoresis and HbA2 estimation were carried out on all. Globin biosynthetic analysis was carried out on all 85 subjects with microcytic red cells and on 180 randomly selected subjects with normal red cell indices. The results showed prevalence of beta-thalassaemia of 3.0%, alpha/beta thalassaemia of 0.9%, alpha-thalassaemia of 43.3% and sickle trait of 5.7%. There were tribal variations in the prevalence of both alpha-thalassaemia and the sickle gene.

A study of alpha thalassaemia families in western Saudi Arabia.

In Saudi Arabia there are three alpha globin chain alleles alpha alpha/, -alpha/, alpha alpha T/-producing six genotypes. In this study of 12 alpha thalassaemia families, the phenotypic expression of these six genotypes is determined. Globin chain biosynthesis gave five non overlapping ratios of 0.9 +/- 0.05, 0.69 +/- 0.06, 0.5 +/- 0.03, 0.38 +/- 0.04 and 0.23 +/- 0.06. The five groups are shown to be normal, alpha thal 2 trait with genotype -alpha/ alpha alpha, mild alpha thal 1 with -alpha/-alpha and alpha alpha/alpha alpha T as genotypes, severe alpha thal 1 with genotype -alpha/alpha alpha T and Hb H disease. The red cell indices MCV, MCH and MCHC of the groups show a step ladder fall. Hb H inclusions in red cells are slight in the mild alpha thal 1 and rises to gross in Hb H disease. The latter disease also shares typical red blood cell appearances with severe alpha thal 1. Hb H disease is relatively mild with no gross bony changes.