J Korean Pediatr Soc.
1996 Jul;39(7):915-923.
Molecular Genetic Screening for the SRY(Sex Determining Region of the Y chromosme) Gene in Turner Syndrome Patients
- Affiliations
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- 1Department of Pediatrics, Asan Medical Center, College of Medicine, Ulsan University, Seoul, Korea.
Abstract
- PURPOSE
Turner syndrome is among the most common cytogenetic abnormalities associated with X chromosome. In only 40-60% of Turner syndrome, 45,X monosomy is found and the high prenatal mortality of non-mosaic 45,X has led to the hypothesis that liveborn 45,X individuals may be cryptic mosaics. The presence of Y chromosome is significant because it predisposes affected individuals with Turner syndrome to gonadoblastoma formation. Until recently, genotype analysis was based mainly on classical cytogenetic techniques, yet it has some limitations to detect Y-derived chromosomal material. In this study, we aimed at molecular genetic screening for the presence of Y-chromosome or derivative by using polymerase chain reaction (PCR).
METHODS
Cytogenetic analysis was performed in patients with clinical features of Turner syndrome. We examined the presence of products of the Y chromosome by polymerase chain amplification of the sex-determining region of the Y chromosome(SRY) gene and repetitive sequences located at the centromeric region(DYZ3), using genomic DNA obtained from peripheral blood lymphocytes of 19 patients with Turner syndrome.
RESULTS
1) Among 19 patients cytogenetically studied, 12 patients carried 45,X; four patients, structural anomalies of the X chromosome; three were mosaics for 45,X, one with 46,XY, another with 46,X+mar, another with 46,X,i(Xq). 2) Three patients yielded a PCR product derived from the SRY gene. In two of them, an Y chromosomal material was not visualized by cytogenetic analysis. 3) Among 3 patients with positive signals for the SRY gene, one patient was negative for DYZ3, suggesting that only a small portion of Y was present.
CONCLUSIONS
The molecular genetic analysis for the detection of Y chromosome is more sensitive than cytogenetic analysis. Prophylactic gonadectomy may be justified in Turner syndrome patients with Y-derived chromosomal material to reduce the risk for the development of gonadoblastoma.
