Presence of typical findings in a phenotypic female with complete or partial absence of the second sex chromosome
Prevalence: 1:2,000 to 5,000 liveborn females
- Genotype frequencies
- 45,X 55%
- 46,Xi(Xq) 17%
- 45,X/46,XX 13%
- 46,Xr(X) 5%
- 45,X/46,XY 5%
- Other 5%
- Recurrence risk is low in subsequent pregnancies in the absence of familial X chromosome defects.
- Deletion of the SHOX gene at Xp22.33 is responsible for the majority of the height deficit in affected patients.
- Fetuses with Turner syndrome have accelerated loss of germ cells from the second half of gestation through the first few years of life, with eventual gonadal failure.
Commonly Associated Conditions
- Short stature (~100%)
- Hypogonadism (90%)
- Sensorineural hearing loss in adults (60%)
- Hypertension (50%)
- Glucose intolerance in adults (40–50%)
- Autoimmune thyroiditis (27%)
- ADHD (24%)
- Conductive hearing loss (21%)
- Renal collecting system abnormalities (20%)
- Strabismus/hyperopia (17%)
- Bicuspid aortic valve (16%)
- Coarctation of the aorta (11%)
- Horseshoe kidney (10%)
- Celiac disease (6%)
- Aortic dissection (1–2%)
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