Turner syndrome
Turner syndrome is a 45,X (or mosaic-variant) chromosomal disorder causing gonadal dysgenesis, short stature, and a characteristic phenotype including webbed neck, coarctation of the aorta, and horseshoe kidney. Karyotype confirms the diagnosis, and management centers on growth hormone in childhood and estrogen-based pubertal induction with lifelong cardiovascular and metabolic surveillance.
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What this article covers
- Overview
Chromosomal gonadal dysgenesis syndrome: Turner syndrome results from complete or partial loss of one X chromosome in a phenotypic female, most often 45,X (monosomy) or a mosaic karyotype such as…
- Epidemiology
Female-only condition: by definition it occurs only in phenotypic females, as a loss of X-chromosome material.
- Risk factors
No modifiable risk factor: Turner syndrome arises from de novo nondisjunction or a postzygotic mitotic error, with no known parental exposure or behavior that raises risk.
- Pathophysiology
Loss of the second X chromosome accelerates ovarian follicle atresia: normal ovarian development requires two intact X chromosomes; with only one, oocytes and follicles undergo accelerated apoptosis…
- Clinical features
Short stature presenting in childhood: the single most consistent finding, often first noted as a decline across growth-curve percentiles well before puberty is expected.
- Differential diagnosis
Primary ovarian insufficiency of another cause (the closest adult mimic): hypergonadotropic hypogonadism without the Turner phenotype, discriminated by a normal karyotype and an autoimmune or…
- Diagnosis
Karyotype analysis on peripheral blood lymphocytes establishes the diagnosis: demonstration of 45,X or a mosaic pattern (for example 45,X/46,XX or 45,X/46,XY) confirms Turner syndrome; phenotype or hormone pattern alone is not sufficient.
- Management
Confirm the karyotype and stage the initial workup before any hormone is started: obtain echocardiogram, renal ultrasound, TSH/free thyroxine, and audiology evaluation, since hearing loss and otitis…
- Complications
Aortic dissection and rupture: the most feared complication, with risk elevated even without coarctation or bicuspid aortic valve; drives lifelong surveillance imaging and blood pressure control.
- Prognosis
Life expectancy is reduced primarily by cardiovascular disease: aortic dissection and coarctation-related complications are the leading drivers of excess mortality, so cardiac surveillance is central…
- Prevention
Karyotype testing whenever short stature or delayed puberty is unexplained: height below the third percentile with no other cause, or absent secondary sexual characteristics by age 13, warrants karyotype analysis.
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