Population structure of the human pseudoautosomal boundary

Abstract

The mammalian sex chromosomes are composed of two genetically distinct segments: the pseudoautosomal region, where recombination occurs between the X and Y chromosomes, and the sex chromosome-specific parts. Between these two segments the human sex chromosomes differ by the insertion of an Alu element on the Y chromosome. We have surveyed the sequence variation in the boundary region using the polymerase chain reaction. Fifty seven Y and sixty X chromosomes from ten different human populations were analysed. The X chromosomes were found to be polymorphic at five positions in a 300-base-pair region. By contrast, all Y chromosomes were identical except for one distal polymorphism shared with the X chromosome.

Human Y-chromosome variation in the Western Mediterranean area: implications for the peopling of the region

“…TAT [21] was typed in all LLY22g(A); 11. XY275Y [22,23] was tested in all YAP(ϩ) and many of the others.…”

“…Strong linkage disequilibrium between XY275 and the boundary has previously been observed [22,23,35], with the T allele occurring on both the X and Y chromosomes at varying frequencies, and the G allele occurring almost exclusively on the X chromosome. Because the association is not absolute, it is feasible that some chromosomes are generated by crossover between the X and the Y, as previously suggested [35].…”

“…Most of the Y chromosomes were also typed for the XY275Y T/G polymorphism [22,23] that is located in the short-arm pseudoautosomal region, 275 bp distal from the boundary, and is shared by the X and Y chromosomes. Strong linkage disequilibrium between XY275 and the boundary has previously been observed [22,23,35], with the T allele occurring on both the X and Y chromosomes at varying frequencies, and the G allele occurring almost exclusively on the X chromosome.…”

PCR detection of structurally abnormal Y chromosomes

“…Very recently, a set of primers for DYSI has been developed based on the 49f-related 49a sequence (Lucotte et al, 1991). An additional five sets of previously reported primers detect additional 5 loci (Ellis et al, 1990;Nakagome et al, 1991aNakagome et al, , 1991bNakahori et al, 1991c;Witt and Erickson, 1989). The loci detected by these eight sets of primers are distributed over the nearly entire length of the Y chromosome.…”

“…Three loci were on the short arm, PABY, SRY, and AMGL. As to the PABY locus, a mixture of the PABA, PABB, and PABC primers simultaneously detects both X-specific (PABX) and Y-specific (PABY) sequences from the proximal border of the pseudoautosomal region (Ellis et al, 1990). The SRY primers have been described by Nakagome et aL (1991b) and are based on the sequences reported by Sinclair et al (1990).…”