[Identification of Y-chromosome by Molecular Analysis in Patients with Turner Syndrome.].
BACKGROUND
It is known that the Y chromosome or Y-specific sequence is present in about 6% of Turner syndrome (TS) patients and that it predisposes them to gonadoblastoma formation with an estimated risk of 15-25%. In this study, we performed a polymerase chain reaction (PCR) in 32 patients with TS to detect Y-specific sequence. The results were compared with those obtained by the fluorescence in situ hybridaization (FISH) method.


METHODS
Cytogenetic analysis was performed by phytohaemagglutinin (PHA)-stimulated peripheral lymphocyte cultures, using G-banding. DNA was extracted from peripheral blood for PCR. Seven different sets of oligonucleotide primers, sex determining region Y (SRY), zinc finger gene on the Y chromosome (ZFY), testis specific protein Y (TSPY), DYZ3, DYF49S1, RNA binding motif protein (RBM), and DYZ1, spanning on centromeres and short and long arms of the Y chromosome were used for PCR. FISH was carried out using X and Y chromosome enumeration probe for Xp11.1-q11.1 (DXZ1 locus) and Yp11.1-q11.1 (DYZ3 locus), respectively.


RESULTS
Among 32 patients with TS, four (12.5%) were positive for Y specific sequence by PCR. Of these, two patients were detected previously by a cytogenetic analysis: 45,X/47,XYY and 45,X/46,XY. Only one Y specific sequence, DYZ3, was detected by PCR in the other two patients without cytogenetically obvious Y chromosome. Y signal was not detected by FISH for the last two patients.


CONCLUSIONS
It may be reasonable to consider using a PCR method to screen for Y-specific sequences in all patients with TS. Even though we did not demonstrate Y-signal by FISH in patients with PCR positive and cytogenetically no obvious Y chromosome, FISH may be another useful method in TS patient, and futher investigation is nessessary.