Association of recombination errors and young mother age in risk of Down Syndrome in South Indian population.

Down syndrome (DS) is caused due to nondisjunction (NDJ) of chromosome 21; 90% of the cases are of maternal origin and is of major public health concern. Maternal age and altered recombination are the two well established risk factors causing NDJ. In the present study we have examined the association between these two factors using short tandem repeat (STR) markers in order to give further insights into the mechanism of NDJ. We have created maternal age stratified recombination profile which includes the recombination frequency and recombination location in 145 cases of mothers with DS and control mothers. Our investigation identifies parental origin, stage of NDJ and recombination pattern. The result from the study indicates Meiosis I NDJ errors are associated with altered recombination and young mother age. Recombination in telomeric region and multiple crossover events marked a significant impact on younger women with DS in the present investigation. In conclusion, our examination reveals recombination error, recombination pattern and maternal age play a major role in chromosomal NDJ and can act as predisposing factors for NDJ of chromosome 21 leading to DS.