Define Turner Syndrome. Describe its clinical features, diagnosis, management and prognosis.

Definition

Turner syndrome is a disorder of females caused by complete or partial absence of one X chromosome (classically 45,X monosomy), resulting in gonadal dysgenesis and short stature.

Cytogenetics

• 45,X (monosomy X) in about half; the rest are mosaics (45,X/46,XX) or have X structural abnormalities (isochromosome, deletions).
• Not associated with advanced maternal age.

Clinical Features

• Short stature — the most consistent feature.
• Neonatal — lymphoedema of the hands and feet and redundant neck skin.
• Webbed neck, low posterior hairline, shield chest with widely spaced nipples, cubitus valgus, short 4th metacarpal, multiple pigmented naevi, high-arched palate.
• Gonadal dysgenesis ('streak ovaries') → delayed/absent puberty, primary amenorrhoea and infertility.
• Usually normal intelligence.

Associated Anomalies

• Cardiac — coarctation of the aorta and bicuspid aortic valve.
• Renal — horseshoe kidney; recurrent otitis media and hearing loss; autoimmune thyroiditis.

Diagnosis

• Karyotype (45,X or variant) is confirmatory; fish for mosaicism.
• Hypergonadotropic hypogonadism — raised FSH and LH with low oestrogen.
• Echocardiography and renal ultrasound for associated anomalies.

Management

• Growth hormone to improve final height.
• Oestrogen replacement to induce puberty and maintain secondary sexual characteristics/bone health.
• Management of cardiac and renal anomalies; hearing and thyroid surveillance.
• Fertility counselling (assisted reproduction/oocyte donation) and psychological support.

Growth & Puberty

• Short stature is present from childhood; specific Turner growth charts are used.
• Most have ovarian failure needing induced puberty; a minority (mosaics) may menstruate/rarely conceive.

Importance of the Karyotype (y Material)

Detecting Y-chromosome material (in some mosaics) is important because it raises the risk of gonadoblastoma, for which gonadectomy is considered.

Psychosocial & Prognosis

Intelligence is usually normal, though specific visuospatial/social difficulties occur; with growth hormone, oestrogen therapy and management of cardiac/renal issues, most women lead healthy, productive lives.

Differential Diagnosis

• Other causes of short stature (GH deficiency, hypothyroidism, skeletal dysplasia) and of primary amenorrhoea.
• Noonan syndrome ('male Turner-like' phenotype but normal karyotype, autosomal dominant, pulmonary stenosis).

Monitoring

• Regular cardiac (aortic dimensions), renal, thyroid, hearing and bone-density review.
• Growth on Turner-specific charts; monitor response to growth hormone/oestrogen.

Neonatal Presentation

• Congenital lymphoedema of the dorsa of hands and feet and loose nuchal skin folds are early neonatal clues.
• A neonate with lymphoedema, a heart murmur (coarctation) or webbed neck warrants a karyotype.

Growth-promoting & Pubertal Therapy

• Growth hormone is started in early childhood to improve final adult height.
• Oestrogen (then oestrogen-progesterone) is introduced at the appropriate age to induce puberty, complete growth and protect bone.

Transition & Adult Issues

• Lifelong follow-up for the aorta (dilatation/dissection risk, especially in pregnancy), hypertension, diabetes, thyroid and hearing.
• Structured transition to adult services with attention to fertility, bone and cardiovascular health.

Fertility & Pregnancy

• Most women are infertile (streak gonads); pregnancy is possible via oocyte donation/assisted reproduction.
• Pregnancy carries a real risk of aortic dissection — cardiac assessment and monitoring are essential beforehand.

WHY the Heart and Kidney Must Be Imaged

• A crucial and easily-forgotten point is understanding why every girl with Turner syndrome needs cardiac and renal imaging — and lifelong cardiac surveillance.
• The absence of the second X chromosome affects the development of several systems, and two of these carry real danger.
• The cardiovascular anomalies — bicuspid aortic valve (the commonest) and coarctation of the aorta — may be entirely silent in childhood.
• But the aorta in Turner syndrome is intrinsically abnormal, and these women are at significantly increased lifetime risk of aortic root dilatation and dissection — which may be fatal, and whose risk rises sharply in pregnancy.
• Hence: an echocardiogram at diagnosis, lifelong monitoring of the aortic root, and careful counselling before any pregnancy.
• The renal anomalies (horseshoe kidney, duplex collecting systems) predispose to infection and obstruction — hence a renal ultrasound.
• And the other lifelong needs must be met: screening for hypothyroidism and coeliac disease, hearing assessment (recurrent otitis media and later sensorineural loss), and management of infertility (streak ovaries — though pregnancy is possible with egg donation).