Quantitative trait transmission disequilibrium test: allowance for missing parents.

The association of a quantitative trait with transmission disequilibrium of parental marker alleles can be a powerful method to discover the genetic basis of the trait. However, current methods require marker genotypes on all parents. We present a new method that allows the assessment of the association of a quantitative trait with transmission disequilibrium of marker alleles when parental marker genotypes are missing, but marker genotypes for sibships are available. Because our approach is based on regression methods, additional covariates, including multiple marker loci, can be included in our proposed method of analysis. Application of this methodology to the COGA data to assess the association of quantitative traits (ERPs) with marker loci on chromosome 7 failed to identify statistically significant transmission disequilibrium.