Karyotype - Phenotype Associations in Patients with Turner Syndrome.

Variation in karyotype may be associated with the phenotype of patients with Turner syndrome (TS). Our objective was to identify these associations between karyotype and phenotype in TS patients. This study was part of the European multicentre dsd-LIFE study. We evaluated the associations between different karyotypes of TS patients and age at diagnosis, Turner stigmata, cardiac/renal involvement and gonadal function. Information was available for 328 TS patients. Participants had a monosomy 45,X (46%), mosaicism 45,X/46,XX (10%), karyotype with isochromosome (18%), or other karyotype (26%). The clinical signs of TS were the most severe in patients with monosomy 45,X and the least severe in patients with mosaicism 45,X/46,XX. Patients with isochromosome and y-material showed an intermediate phenotype. Despite the more severe features in patients with monosomy 45,X, the median age at diagnosis was only slightly lower compared to patients with other karyotypes, which suggests opportunities for improvement of knowledge and diagnostics.