BackgroundTurner Syndrome (TS) is a frequently identified chromosomal disease in humans characterized by short stature, sexual infantilism, streak gonads, primary amenorrhea, and a number of somatic anomalies. Approximately 55% of TS individuals have a nonmosaic 45,X karyotype. In addition, a cell line with a Y chromosome is present in 5% of patients, which is undetectable by the standard cytogenetic analysis. The identification of Y chromatin in some TS individuals has been associated with the development of gonadoblastoma. Therefore, it is important to exclude the presence of Y chromatin in TS individuals. In this study, it was planned to detect cases with mosaicism in terms of Y chromatin with the help of Y whole chromosome probes (WCP) from individuals with TS by fluorescence in situ hybridization (FISH) analysis. MethodologyForty-four patients with Turner syndrome, who were being followed up in the Genetics Unit, were contacted and invited for the study. Of the 44 invited patients, 28 responded to the invitation. In this study, it was planned to detect TS patients with mosaicism in terms of Y chromatin with the help of the Y whole chromosome probe. ResultsThe majority of the cases (71.42%) included in the study carried pure X monosomy, which is the classical Turner syndrome karyotype. Other structural X chromosome aberrations, in isolated or mosaic forms, were less frequently represented. Y chromosome sequences were searched in 28 cases with Turner syndrome by the FISH method using Y whole chromosome probe. Y chromosome sequence was detected in one (3.5%) case of 28 cases. ConclusionsIt is recommended that individuals with Turner syndrome be screened for Y chromatin. Detection of this will provide information and guidance to individuals with Turner syndrome, especially in terms of the risk of developing gonadoblastoma, with advanced clinical consultation. This study was conducted to emphasize the importance of this.