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ABSTRACT |
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| Molecular cytogenetic characterisation of rare telomere-telomere (Yp;17p) and (Yp;Yp) fusion/translocations in a male with oligospermia | |||
| Adrianne Ralph1, Emily Vardy1, Jasen Anderson1, Anthony Watson1, Judy Collis1, Ross Brookwell1 and John Allan2 | |||
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1 Cytogenetics Department, Sullivan Nicolaides Pathology, P.O. Box 344, Indooroopilly, Queensland, Australia. 2 Wesley IVF, Wesley Hospital, Auchenflower, Queensland, Australia. |
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Male infertility may be due to a variety of genetic mechanisms. We report here, for the first time, telomere-telomere fusion/translocations (tas) involving the Yp and 17p in a 50-year-old male with oligospermia. In 45 of 58 GTG banded lymphocytes examined, the Yp telomere was fused with one 17p telomere, tas(Yp;17p). In 13 cells, the Yp was fused with another Yp, tas(Yp;Yp). Molecular cytogenetic characterisation using FISH probes for 17p and Yp subtelomeres, 17 and Y centromeres and SRY (Vysis) and whole chromosome paints for chromosomes 17 and Y (Cambio) indicates the 17p and Yp are intact. In the tas(Yp;17p) cell line, this infers a non-reciprocal or terminal fusion/translocation with no chromosomal imbalance. In the tas(Yp;Yp) cell line, the genotype is effectively XYY. Telomere fusion rearrangements are extremely unusual among constitutional chromosome abnormalities and there is no similar published case involving the Y chromosome. Rivera et al (1999) report rearrangements leading to interstitial telomeric sequences, the majority of which involve one telomeric and one non-telomeric site. Rossi et al (1993) report an example of a terminal rearrangement involving the telomeres of 17p and 22q fusing in a phenotypically normal female detected at cytogenetic prenatal diagnosis. Most men with mosaic or non-mosaic XYY genotype are not distinguishable from the general population and are fertile (Evans et al 1990). There has been an association demonstrated between these types of rearrangements and infertility (Guichaoua et al 1992). In male meiosis, the X and Y chromosomes pair at their distal short arms. In this case Yp is translocated/fused in both cell lines and is therefore not free to synapse with the X. This would most likely result in spermatogenic arrest.
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Abstracts will be published by Elsevier (Annales de Génétique) |
