DETECTION OF Y-CHROMOSOME SEQUENCES IN TURNERS-SYNDROME BY SOUTHERN BLOT ANALYSIS OF AMPLIFIED DNA

Only about half of all patients with Turner's syndrome are monosomy 45 ,X on karyotyping and there are grounds for supposing that cryptic mos aicism for at least part of the Y chromosome may be present in some pa tients. If so this would be clinically important because of the risk t o patients of gonadal neoplasms and virilisation. We have used a very sensitive method to detect Y chromosomal segments in eighteen patients with Turner's syndrome, none of whom had evidence of Y chromosomal ma terial by cytogenetic analysis. In DNA from peripheral blood lymphocyt es and/or fibroblasts we looked for specific nucleotide sequences from the sex-determining region of the Y chromosome (SRY gene) and repetit ive sequences located at the centromeric region (DYZ3). By polymerase chain amplification (PCR) one patient had a definite positive signal a nd two patients had faintly positive signals for the SRY gene. Souther n blot analysis of PCR material with a SRY-specific probe confirmed th at these patients were positive for SRY and revealed another three. No patient was positive for DYZ3, suggesting that only a small portion o f Y was present. These results suggest that ''pure'' 45,X monosomy is less frequent than previously supposed. Long-term follow-up of patient s with Y sequences is needed to determine their risk for subsequent go nadal neoplasms and virilisation.