Turner syndrome is a sex chromosome disorder in phenotypic females caused by complete or partial absence of one X chromosome (45,X karyotype), leading to short stature, ovarian dysgenesis (streak gonads), and characteristic physical features such as a webbed neck.
It is the most common sex chromosome abnormality in females (~1 in 2500 births) and a major cause of short stature and primary amenorrhea. Frequently tested on exams as it spans genetics, endocrinology (puberty, infertility), and congenital anomalies (cardiac, renal).
Many girls are diagnosed in adolescence due to short stature (growth stops early) and lack of puberty (amenorrhea with no breast development). Classic findings include a webbed neck, low posterior hairline, shield chest (broad chest, widely spaced nipples), and cubitus valgus (increased carrying angle at elbows).
Coarctation of the aorta (diminished femoral pulses, differential arm/leg BP) or bicuspid aortic valve occur in ~30%. Other features: congenital lymphedema (swollen hands/feet at birth leading to the webbed neck), high-arched palate, low-set ears, horseshoe kidney, and hearing loss (from frequent otitis media). Intelligence is usually normal, though some have specific learning difficulties (e.g., spatial perception/math).
Suspect Turner in any phenotypic female with unexplained short stature or delayed puberty. Confirm the diagnosis with karyotype analysis (45,X or mosaic); expect ↑FSH/LH and low estrogen (hypergonadotropic hypogonadism).
If karyotype shows any Y chromosome material, perform prophylactic gonadectomy to prevent gonadoblastoma (malignancy in streak gonads).
Evaluate for associated anomalies: do an echocardiogram (check for coarctation, bicuspid aortic valve) and renal ultrasound (horseshoe kidney or other malformations). Also screen for hypothyroidism (autoimmune thyroiditis is common) and hearing deficits.
Provide counseling on infertility (nearly all patients cannot conceive naturally, though IVF with donor eggs is sometimes possible).
Condition
Distinguishing Feature
Noonan syndrome
short stature & neck webbing like Turner but normal karyotype; affects both sexes, often has pulmonic stenosis (right-sided heart defect)
Androgen insensitivity syndrome
46,XY with female appearance, tall stature, no uterus (amenorrhea) but normal breast development (testes present)
Müllerian agenesis (MRKH)
46,XX with congenital absence of uterus → primary amenorrhea but normal ovaries (normal breast and hair development)
Growth hormone therapy in early childhood to boost adult height (start as soon as growth delay is identified).
Estrogen replacement therapy (with cyclic progestin) starting in mid-childhood or early teens to induce breast development, initiate menses, and prevent osteoporosis.
Routine management of comorbidities: e.g. monitor and treat hypothyroidism, manage hypertension if present, periodic cardiac MRI/echo to surveil aorta, and support for hearing or learning issues.
Fetal cystic hygroma (large septated nuchal translucency on ultrasound) is a prenatal red flag for Turner syndrome.
Remember "XO": one X chromosome present, and Ovaries are missing (streak ovaries → no estrogen, no puberty).
Patients have no Barr body (no inactivated X) on their karyotype smear.
Coarctation of aorta or undiagnosed aortic dilation can lead to life-threatening aortic dissection or rupture—monitor aortic size and control blood pressure.
Pregnancy (even with donor eggs) is high-risk in Turner patients due to aortic dissection; thorough cardiovascular evaluation is mandatory beforehand.
Any Y chromosome on karyotype → perform gonadectomy to prevent gonadoblastoma (malignant tumor arising in dysgenetic gonadal tissue).
Short-stature girl or primary amenorrhea (no puberty) → karyotype analysis for Turner syndrome.
If 45,X or mosaic karyotype confirmed → evaluate for anomalies (echo for heart defects, renal ultrasound, thyroid studies).
Treat short stature with growth hormone; induce puberty with estrogen at the appropriate age (plus progestin if uterus present).
Lifelong follow-up: regular cardiac monitoring (aorta), endocrine care (thyroid, diabetes screening), and discuss fertility options (e.g., adoption or assisted reproduction).
Teenage girl, 14–16, with short stature, no breast development, and no menarche; physical exam shows a webbed neck and broad chest → Turner syndrome (45,X).
Newborn girl with lymphedema of hands and feet and a neck mass (cystic hygroma), later found to have coarctation of the aorta → Turner syndrome.
Case 1
A 15‑year‑old girl is evaluated for short stature and lack of pubertal development.
Diagram of a female with Turner syndrome displaying physical features such as short stature, webbed neck, broad chest, and streak ovaries (gonadal dysgenesis).
