Use of siblings as controls in case‐control association studies

摘要: The transmission disequilibrium test (TDT) is a simple means to detect association which should only be positive if the marker allele linked disease locus, but it cannot used parents of affected subjects are unavailable, as can occur when has late age onset. Although one sometimes deduce parental genotypes using siblings cases, reliance on this procedure introduce bias and may also result in discarding many families could provide useful information. Instead, shown that use unaffected controls is, like TDT, robust against due population stratification other sources, expected produce results both associated with locus. method have much less power than case-control study unrelated controls, guarded by seeking genotypically distinct from cases focusing alleles different within pairs controls. This yields pair-wise for multiallelic markers manner exactly analogous extended TDT (ETDT). simple, robust, practical worthy further consideration.