HEREDITARY ANEMIAS AND IRON-DEFICIENCY IN A TRIBAL POPULATION (THE BAIGA) OF CENTRAL INDIA

We have studied the prevalence and molecular nature of hereditary anae mias (abnormal haemoglobins, beta-thalassaemia, alpha-thalassaemia, an d Glucose 6 phosphate dehydrogenase (G6PD) deficiency) in a primitive central Indian tribe, the Baiga. 43 % of the population appear to be i ron-deficient. Hereditary anaemia gene frequencies are, sickle cell 0. 0824, G6PD deficiency (in males) 0.0457, beta-thalassaemia 0.0057, and deletional alpha-plus thalassaemia 0.65. Both -alpha(3.7) and -alpha( 4.2) deletions were observed and non-deletional alpha-thalassaemia was suspected. The overall gene frequency of Xmn I + polymorphism (C-->T -158 cap site; upstream of G gamma region) is 0.35. This polymorphism is preferentially linked to beta(s) genes. It appears that sickle cell disease covers a wide range of severity in the Baiga tribe based on h igher mortality in the offspring of AS x AS parents (2.5/couple) compa red to AA x AS (0.75/couple) and AA x AA (0.76/couple) parents. This i s compatible with the high frequency of genetic modifying factors, i.e ., the Xmn I polymorphism and alpha-thalassaemia. The results also ind icate that ''normal'' red cell values must be defined for each populat ion where thalassaemias, G6PD deficiency and iron deficiency are commo n.