Reconstructing hominid Y evolution: X-homologous block, created by X-Y transposition, was disrupted by Yp inversion through LINE--LINE recombination

• DOI: 10.1093/hmg/7.1.1
• Publication Date: 2002-07-26T18:20:49Z
• Authors: A. Schwartz; D. C. Chan; L. G. Brown; R. Alagappan; D. Pettay; C. Disteche; B. McGillivray; A. de la Chapelle; D. C. Page
• Keywords: Chromosomal inversion; Transposition (logic); Breakpoint; Non-allelic homologous recombination

The human X and Y chromosomes share many blocks of similar DNA sequence. We conducted mapping nucleotide sequencing studies extensive, multi-megabase homologies between Yp Xq21, which do not recombine during male meiosis. confirmed built upon previous evidence that a inversion had occurred evolution: single contiguous segment Xq21 is homologous to two non-contiguous segments Yp. precisely defined sequenced the breakpoints, obtaining was mediated by recombination LINE-1 elements in otherwise non-homologous regions. This appears have followed transposition an approximately 4 Mb from chromosome. These events jointly account for present arrangement Yp-Xq21 sequences. Based on Southern blotting primates humans drawn diverse populations, we conclude both X-Y subsequent, LINE-mediated after divergence hominid chimp lineages but before radiation extant populations. evolutionary scenario consistent with our finding 99.3 +/- 0.2% identity within transposed region, suggests 3-4 million years ago, near time emergence Homo . Comparative entire may reveal succession transpositions, inversions other rearrangements underlying complex pattern sequence similarities present-day sex chromosomes. With possible exception cubitus valgus, phenotypic features Turner syndrome are absent individuals monosomic sequences, suggesting most critical 'Turner genes' found elsewhere