Transmission Disequilibrium Test

The Transmission Disequilibrium Test (TDT) is a family-based statistical method for testing genetic association with disease or traits while inherently controlling for population stratification. Developed by Spielman and Ewens in 1993, the TDT examines whether an allele is preferentially transmitted from heterozygous parents to affected children compared to unaffected children. By comparing transmission patterns within families, the TDT avoids the confounding effects of population structure that plague case-control studies, making it particularly valuable in admixed or stratified populations.