Contribution of Marital Distance to Community Inbreeding, Homozygosis, and Reproductive Wastage for Recessively Inherited Genetic Disorders in Madhya Pradesh, India

BACKGROUND Recessively inherited genetic disorders such as sickle cell anemia and β-thalassemia are commonly encountered in heterozygous and homozygous form in India. These hemolytic disorders cause a high degree of reproductive wastage in vulnerable communities. Inbreeding is usually the mating between two related individuals. Homozygosis is antagonistic process of heterosis. PURPOSE This study was aimed at finding reproductive outcome in carrier couples of sickle cell anemia, and β-thalassemia in terms of reproductive wastage in relation to varied marital distance between partners in Madhya Pradesh. METHODS A total of 107 carrier couples, 35 and 72, respectively of β-thalassemia major and sickle cell anemia with confirmed affected offspring after taking detailed reproductive history were studied following the standard methodology in a tertiary hospital in Central India during March 2010 to February 2013. RESULTS A majority of sickle cell and β-thalassemia carrier couples, 77.8% and 65.7%, respectively, had married within physical distance of radius less than 50 kms. away from their native places. It was found that as the marital distance between two carrier partners of above disorders decreases, the number of abortions, still-births, neonatal mortality, infant mortality, and mortality under 10 years age increases, and vice versa, implicating inbreeding and homozygosis. The overall reproductive wastage of 28.2% and 18.6% was recorded in carrier couples of sickle cell disease and β-thalassemia, respectively. This combined reproductive wastage is negatively correlated (r= -0.74; p<0.001) to physical marital distance between the life partners. CONCLUSIONS Relative small population size clubbed with small marital distance leads to inbreeding resulting in homozygosity which increases chances of affected offspring by recessive or deleterious traits and contributes to decreased fitness of a couple or population in Central India.