Phenotypic variation within European carriers of the Y-chromosomal gr/gr deletion is independent of Y-chromosomal background

Csilla Krausz, Claudia Giachini, Yali Xue, Moira Kathleen O'Bryan, Joerg Gromoll, Ewa Rajpert-de Meyts, Rafael Oliva, Isabelle Aknin-Seifer, Edit Erdei, Niels Jorgensen, Manuela Simoni, Jose Luis Ballesca, Rachel Levy, Giancarlo Balercia, Paola Piomboni, Eberhard Nieschlag, Gianni Forti, Robert I McLachlan, Chris Tyler-Smith

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BACKGROUND: Previous studies have compared sperm phenotypes between men with partial deletions within the AZFc region of the Y chromosome and non-carriers, with variable results. In this study, a separate question was investigated, the basis of the variation in sperm phenotype within gr/gr deletion carriers, which ranges from normozoospermia to azoospermia. Differences in the genes removed by independent gr/gr deletions, the occurrence of subsequent duplications or the presence of linked modifying variants elsewhere on the chromosome have been suggested as possible causal factors. This study set out to test these possibilities in a large sample of gr/gr deletion carriers with known phenotypes spanning the complete range. RESULTS: In total, 169 men diagnosed with gr/gr deletions from six centres in Europe and one in Australia were studied. The DAZ and CDY1 copies retained, the presence or absence of duplications and the Y-chromosomal haplogroup were characterised. Although the study had good power to detect factors that accounted for >or=5.5 of the variation in sperm concentration, no such factor was found. A negative effect of gr/gr deletions followed by b2/b4 duplication was found within the normospermic group, which remains to be further explored in a larger study population. Finally, significant geographical differences in the frequency of different subtypes of gr/gr deletions were found, which may have relevance for the interpretation of case control studies dealing with admixed populations. CONCLUSIONS: The phenotypic variation of gr/gr carriers in men of European origin is largely independent of the Y-chromosomal background.
Original languageEnglish
Pages (from-to)21 - 31
Number of pages11
JournalJournal of Medical Genetics
Issue number1
Publication statusPublished - 2009

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