🧭 When to suspect

Turner syndrome is the complete or partial loss of one X chromosome in a phenotypic female.

• The classic karyotype is 45,X, but around half of cases are mosaic (e.g. 45,X/46,XX) or carry a structural X abnormality, producing a milder and easily-missed picture.

• Turner syndrome affects roughly 1 in 2,000–2,500 females.

• It touches almost every system across the lifespan, so it needs lifelong, multidisciplinary care.

Recognition matters most, because diagnosis is too often late – the median age at diagnosis is around 15 years, and some women are not diagnosed until adulthood.

• Short stature is the most consistent feature and is present in almost everyone.

• The second hallmark is ovarian insufficiency (delayed puberty, primary amenorrhoea, infertility).

• A karyotype confirms the diagnosis.

Life stage	Features that should prompt testing for Turner syndrome
Antenatal	Raised nuchal translucency or cystic hygroma, fetal hydrops, or a cardiac (coarctation) or renal (horseshoe kidney) anomaly on ultrasound.
Neonatal	Lymphoedema of the hands and feet, a webbed neck or redundant nuchal skin folds, or a left-sided heart lesion.
Childhood	Short stature or a falling height velocity, webbed neck, widely spaced nipples, a wide carrying angle, or recurrent otitis media.
Adolescence	Delayed or absent puberty, primary amenorrhoea (no periods by 15), absent pubertal growth spurt, or lack of breast development.
Adulthood	Short stature with primary ovarian insufficiency, unexplained infertility, or recurrent miscarriage – consider at any age, as late diagnosis is common.

Have a low threshold in any girl with unexplained short stature (height below the familial range, or crossing centiles downward) and in any woman with primary ovarian insufficiency or unexplained infertility.

Source: International Turner Syndrome Consensus 2024 · NHS Genomics Education

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