With an incidence of 1:2,500 in female newborns, Turner syndrome is one of the most common chromosomal disorders. Affected individuals often exhibit short stature and primary amenorrhea. Although the majority (approx. 55%) of patients have a pure monosomy X, gonosomal mosaics and X-linked structural anomalies also occur.
Also called
- 45,X
- Bonnevie-Ullrich syndrome
- Monosomy X
- Turner's syndrome
- Ullrich-Turner syndrome
Symptoms
Main symptoms include:
- Short stature (approximately 150 cm)
- Primary amenorrhea (delayed or absent menstrual periods)
Other symptoms include:
- Congenital heart defects in up to one-half of those with Turner syndrome
- Facial dysmorphic signs such as outwardly sloping eyelids, low set ears, low hairline
- Gonadal dysgenesis (undeveloped ovaries)
- Broad chest
- Kidney defects
- Skeletal abnormalities
- Swollen or puffy hands and feet (lymphedema)
- Webbed neck
Intelligence is within the normal range.
Prenatally, dilatation of the lymphatic vessels with lymphedema and cystic hygroma is common.
Frequency
Turner syndrome is one of the most common chromosomal disorders, with an incidence of 1:2,500 in female newborns and an estimated 1:100 conceptions (98% of these pregnancies end in miscarriage in the 1st trimester).
Cause
Turner syndrome occurs when a female has X instead of two X chromosomes. In about 55% of patients, a complete monosomy X is present, whereas in the remaining patients, there are gonosomal mosaics or X-linked structural anomalies.
Inheritance
Most cases of Turner syndrome occur at random and are not inherited. Turner syndrome caused by structural chromosome changes can be inherited.
Screening and diagnosis
Prenatal ultrasound may reveal early cystic hygroma or hydrops fetalis, leading to invasive prenatal screening and detection of the chromosomal disorder.
Treatment
Hormone treatment is necessary for the development of secondary sexual characteristics. Although there is no growth hormone deficiency, growth in many patients can be improved by supplementary growth hormone therapy.
Where there is 45,X/46,XY mosaicism, sonographic monitoring of the gonads is recommended due to an increased risk of gonadoblastoma.
Differential diagnosis
Noonan syndrome should be considered as the primary differential diagnosis.
References
Boucher et al. 2001, J Med Genet 38:591 / Ogata et al. 2001, J Med Genet 38:1 / Wieacker 2001, Medgen 13:3 / Tarani et al. 1998, Gynecol Endocrinol 12:83 / Swillen et al. 1993, Genet Counsel 4:7
MedlinePlus [Internet]. Bethesda (MD): National Library of Medicine (US); [updated 2020 Jun 24]. Turner syndrome; updated1 Aug 2023. Available from https://medlineplus.gov/genetics/condition/turner-syndrome/. Accessed 17. Mar. 2025.
“Turner Syndrome.” National Organization for Rare Disorders, 20 Nov. 2023, rarediseases.org/rare-diseases/turner-syndrome/. Accessed 17. Mar. 2025.
