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). Am. J. Med. Genet. 91:99–101, 2000. © 2000 Wiley‐Liss, Inc.