INBREEDING AND ITS CLINICAL CONSEQUENCES: A BRIEF REVIEW WITH SPECIAL REFERENCE TO INDIA

One of the major goals of genetic epidemiology is to identify risk factors, both environmental and familial, and to measure their magnitudes. The assessment of familial or genetic risk factors needs careful statistical evaluation and interpretation. In most populations, the mobility of individuals and the consequent mobility of their gametes are usually restricted. That is, individuals confined in a given area tend to mate with others that are close at hand and thereby determine the gene combination in future generations. In human societies, however, certain preferences are always involved for the selection of mate. The factors include social, religious, linguistic, economic, cultural and territorial (Timaizumi, 1986). Inbreeding, in general, is a genetic consequence of matings which occur between genetically related persons with at least one common ancestor. The understanding of inbreeding is simplified by the distinction between identity of genes by descent and identity by nature. Malecot (1948) pointed out that an individual who is homozygous for a given gene, carries at a certain locus two homologous genes that are physically identical but not necessarily identical by descent. This physical identity is called identity by nature. Inbreeding makes an individual homozygous for genes that are identical by descent. In the present review an attempt is being made to find out the level of inbreeding in India and its possible clinical consequences.