Gender verification in sports by PCR amplification of SRY and DYZ1 Y chromosome specific sequences: presence of DYZ1 repeat in female athletes.

OBJECTIVE: To perform genetic sex typing during the Barcelona Olympic Games using polymerase chain reaction (PCR) amplification of Y chromosome specific sequences. METHODS: The assay consisted of the amplification of a specific sequence corresponding to the repeat DYZ1 element from buccal smears samples of 2406 female competitors. Positive samples were reanalysed for the presence of another Y chromosome specific gene, SRY. RESULTS: The expression of these two elements did not always correlate; six samples were found where the presence of DYZ1 but not SRY was detected. This presence of DYZ1 sequence in female athletes is higher than in unselected females, where no DYZ1 amplification was observed in any of the 1629 samples analysed. CONCLUSIONS: Amplification of DYZ1 repeat should not be used as the only index for determining genetic sex, at least in sporting events.