RT Book, Section A1 Bianchi, Diana W. A1 Crombleholme, Timothy M. A1 D'Alton, Mary E. A1 Malone, Fergal D. SR Print(0) ID 1106402109 T1 45, X (Turner Syndrome) T2 Fetology: Diagnosis and Management of the Fetal Patient, 2e YR 2015 FD 2015 PB McGraw-Hill Education PP New York, NY SN 978-0-07-144201-5 LK obgyn.mhmedical.com/content.aspx?aid=1106402109 RD 2024/10/10 AB Key PointsMost common chromosomal abnormality that occurs in females. Only 1%of conceptuses with Turner syndrome survive to term.Incidence is 1 in 2500 female livebirths. No association with advanced maternal age.Approximately 50% of cases have full 45, X, 30% to 40% have mosaicism, and 10% to 20% have a structural abnormality of one X chromosome. Severity of clinical phenotype cannot be predicted from the karyotype.Characteristic sonographic abnormalities include very large cystic hygroma, hydrops fetalis, short femur, coarctation of the aorta, hypoplastic left heart, and renal anomalies.In the presence of lymphatic or cardiac malformations, delivery should occur at a tertiary center.Major considerations for long-term follow-up include: growth hormone treatment for short stature, estrogen treatment for feminization and bone health, monitoring for cardiovascular complications such as aortic dilatation and rupture, severe hypertension, and propensity toward autoimmune disease.Intelligence is normal, but there may be mild learning difficulties related to visual-spatial issues.Phenotype may differ depending upon whether the maternal or paternal X is retained. In ~75% of women the maternal X remains.