The mouse t complex distorter-3 (Tcd-3) locus and transmission ratio distortion.

A novel central partial t haplotype was generated by screening for a recombination event between overlapping distal and proximal partial haplotypes. This haplotype contains just two elements--Tcrt and Tcd-3t--involved in the t-specific transmission ratio distortion phenotype. Breeding analysis of males that carry this chromosome provides evidence that Tcd-3 is, indeed, a distorter locus and not a second responder. Furthermore, the data indicate that a single well-defined distorter locus is insufficient to overcome completely the self-destructive, low transmission ratio distortion phenotype expressed by the t allele at the t complex responder locus, although a small, but highly significant, effect was observed.