Molecular basis of the TaqI p49a,f polymorphism in the DYS1 locus containing DAZ genes.

ABSTRACT

The previously described TaqI p49a,f polymorphism at the DYS1 locus in the non-recombinant part of the Y chromosome is widely exploited to investigate many facets of human population genetics. It has been shown that the DYS1 locus corresponds to the four DAZ genes in the AZF-c region of the Y chromosome. As the DNA sequence of the DAZ genes is known in its entirety, it is now possible to establish correspondences between the main Southern polymorphic TaqI bands (A, C, D, F and I) at the DYS1 locus and TaqI fragments deduced from the sequence, by way of comparing band sizes and sequence homologies between hybridized fragments. Transitions between polymorphic forms for each variable TaqI fragment can be explained regarding the restriction maps, by postulating a parsimonious number of TaqI site losses during human evolution. Most of the codon changes caused by TaqI site losses located in the exons of the four DAZ genes have potentially high selective values.