Objective: To estimate the prevalence of beta-thalassaemia in different subcastes of the Indian Sindhi population who, in general, have a high prevalence of this disease.
Study design: A two-phase, community-based survey.
Methods: Asymptomatic, Sindhi volunteers from Nagpur, central India, were recruited into the present study over a 7-year period. The first phase included the use of the Naked Eye Single Tube Red cell Osmotic Fragility Test (NESTROFT). Those positive for NESTROFT or those volunteering for haemoglobin A(2) (HbA(2)) quantification entered the second phase of the survey. Appropriate statistical methods for estimating prevalence from two-phase surveys were used.
Results: The prevalence of beta-thalassaemia carriers across the five major Sindhi subcastes varied substantially in the study population. Larkana Sindhis had the highest (17%) whereas Dadu Sindhis had the lowest (8%) frequency of the beta-thalassaemia allele. As a corollary, the projected incidence of beta-thalassaemia major in newborn babies greatly varied by the subcastes of the parents.
Conclusion: Ethnic subgroups within populations known to commonly carry the beta-thalassaemia gene provide further information that is useful from epidemiological and public health perspectives.