Mutation Analysis of Beta-thalassaemia in 30 Families of India: A Report

Abstract

Introduction: The β-thalassaemia is one of the haemoglobinopathies related to genetic disorders. It occurs due to mutation in β-gene of autosome 11. In India, it affects 1-7% of couples annually. Reports are available in few states of India about β-thalassaemia affected families. But much data is not reported in families of various states of India. Further, the incidence of case index and mutations in parents and siblings of these families are limited. Aim: To analyse patient case index and mutation analysis of parents and siblings {Children and Chorionic villus sampling/ Amniotic fluid (CVS/AF) cases} of 30 families of India and to develop preventive measures. Materials and Methods: A total of 101 referral cases of 30 families filled consent forms and then blood was drawn in a sterilised tube from each case (71) for the study. The AF/ CVS (30) were also included. The red cell markers like Mean Corpuscular Volume (MCV), Red Cell Distribution Width (RDW) etc., biochemical, case types and molecular analysis were done using respective techniques for red cell indices, Haemoglobin (Hb) types and mutation analysis. Results: We report a number of 30 referral families (101 cases) having parents (60), children (11) and CVS/AF samples (30) for their β-thalassaemia, as these traits also cause β-gene mutations. Out of these 101 cases, 88 (87%) cases were positive for this disease. Only 74 (73%) were detected carriers. The case analysis in present cohort indicated parents (56.5%), CVS/AF (19.8%) and proband (children) (10.9%) were found affected. All children moreover, were affected and did, not have CVS/AF samples. The mutations analysis, indicated c.92+G>C (50/94; 53.19%) was maximum and parents contributed 62% followed by siblings (38%) with CVS/AF (22%) and proband (16%) in present cohort. Thus, in the present study, mutation analysis further pointed out that parents transmit these to the offsprings in the subsequent generation who would be the targets of thalassaemia disease. Conclusion: The present study, points out that mutations transfer from parents to offspring follows the laws of inheritance. Case index study showed parents constituted high percent of cases followed by CVS/AF and children/probands, comparable to mutation analysis in present cohort. Hence, carrier parents must undergo counseling and genetic testing to confirm their genetic disorder to limit the burden of the disease.

Keywords

• beta-thalassaemia traits
• red cell markers
• referral cases