Isodicentric Y chromosome in an Ullrich-Turner patient without virilization

We report on a 17-year-old young woman with Ullrich-Turner syndrome (UTS), who was found to have a karyotype 45,X/46,X,idic(Y)(q11). She had age-appropriate genitalia without virilization in spite of the presence of the Y-derived marker chromosome and SRY locus in 70% of her lymphocytes. Having reviewed the literature, we conclude that a possible explanation for the lack of virilization in these mosaic patients is most likely an uneven distribution of tissue mosaicism (gonadal mosaicism).