45,X/46,X,+r(X) can have a distinct phenotype different from Ullrich-Turner syndrome.
We present a patient with 45,X/46,X,+r(X) mosaicism and lack of inactivation of either the normal or the ring X in the 46,X,+r(X) cells. The patient has mental retardation, syndactyly, minor facial anomalies, and a congenital heart defect. Although most patients with 45,X/46,X,+r(X) have the Ullrich-Turner syndrome, 2 previously described patients with this karyotype also had a distinct phenotype consisting of severe mental retardation, syndactyly, and abnormal face. The unusually severe phenotype in these patients was thought to be due to lack of X-inactivation of the ring X chromosome. The findings in our patient support this hypothesis.
Grompe
M
M
Institute for Molecular Genetics, Baylor College of Medicine, Houston, Tex 77030.
Rao
N
N
Elder
F F
FF
Caskey
C T
CT
Greenberg
F
F
D000328:Adult; D002675:Child, Preschool; D004303:Dosage Compensation, Genetic; D005145:Face / Q000002:abnormalities; D005260:Female; D006330:Heart Defects, Congenital / Q000235:genetics; D006801:Humans; D008607:Intellectual Disability / Q000235:genetics; D008297:Male; D009030:Mosaicism; D010375:Pedigree; D010641:Phenotype; D012303:Ring Chromosomes; D013576:Syndactyly / Q000235:genetics; D014424:Turner Syndrome / Q000235:genetics*; D014960:X Chromosome