Genetic analysis of Turner syndrome: 89 cases in Tunisia

Turner's syndrome (TS) affects about 1/2500 female infants born alive. The syndrome results from total or partial absence of one of the two X chromosomes normally present in females. We report the results of a retrospective analysis of 89 cases of TS observed during a six-year period (2000-2005). The patients' age ranged from two days to 51 years at the time of this analysis. Most patients were adults (48%). The aim of this study is to ascertain the principal clinical features leading to a request for a karyotype, searching for a possible relationship between chromosomal anomalies and clinical expression of TS. Pediatric patients were referred for statural retardation or dysmorphic features, while reproduction anomalies were the main indication for karyotyping in patients aged over 20 years. Mosaicism was prevalent (47%), whereas the homogeneous karyotype 45,X was found in only 32% of the patients; structural anomalies were found in 21%. Regarding the advanced age of our patients, we established a relationship between chromosome anomalies and the clinical expression of TS, based on an analysis of stature and reproduction disorders. Short stature and primary amenorrhea were correlated with total deletion of one chromosome X or imbalanced gene dosage due to structural X anomalies. Whereas cases of infertility, recurrent miscarriages and secondary amenorrhea were associated with a mosaic karyotype pattern (45,X/46,XX or 45,X/46,XX/47,XXX ...), with a slight mosaicism in most cases. Thus, chromosome investigations should be performed in cases of reproduction failure even for women with normal stature.