Frequencies and distributions of sex chromosome abnormalities in females with the Turner phenotype: a long-term retrospective study in the southern region of Turkey

Background/aim: The genetic background of Turner syndrome (TS) is highly variable. The correlation between genotype and phenotype is not yet well understood. The aim of this study was to describe the frequencies and distributions of Turner karyotypes and to discuss the phenotype/genotype relation in a very large group of individuals with TS. Materials and methods: The karyotype results of 248 female participants were evaluated retrospectively.Results: Of 248 females with the Turner phenotype, 14.5% had normal karyotypes and 85.5% had Turner karyotypes. About 72.2% of the abnormalities were numerical aberrations and 27.8% were structural aberrations. The most frequent karyotype was monosomy X, which was found in 135 females (63.7%), followed by 44 mosaics (21%), 40 isochromosomes of the long and short arms of chromosome X (19.1%), and 17 deletions of the short and long arms of chromosome X (8.0%). One case of Robertsonian translocation and one case of mosaic TS with marker chromosome were detected. Conclusion: This study shows the frequency and distribution of karyotypes in females with TS. There is great value to be gleaned from studies of females with TS in furthering our understanding of the atypical clinical features associated with TS. Studies involving genetic analyses will be necessary to examine gene expression profiles in girls with TS and identify potential candidate genes underlying the atypical clinical features associated with TS.