Medical Genetics

Turner syndrome

A sex-chromosome condition caused by complete or partial loss of one X chromosome, usually 45,X or mosaic, with variable short stature, ovarian insufficiency and characteristic cardiac, renal, hearing, metabolic and learning needs; aortic disease makes lifelong cardiovascular care essential.

In a nutshell

Turner syndrome is complete or partial loss of one X chromosome, usually 45,X or mosaic. Short stature and ovarian insufficiency cause delayed or absent puberty and infertility, while congenital heart disease, a generalized aortopathy, hypertension, renal anomalies, thyroid and coeliac disease, hearing loss, bone disease and specific learning or psychosocial needs require lifelong surveillance. Confirm with chromosome analysis, offer specialist growth hormone and staged oestrogen replacement when indicated, and plan pregnancy or fertility treatment through an expert cardiac-maternal MDT.

Classic presentation

A short adolescent with webbed neck, widely spaced nipples, absent breast development and primary amenorrhoea has raised FSH and LH, a 45,X karyotype and a bicuspid aortic valve on cardiac imaging.

Key points

Turner syndrome includes 45,X, mosaic and structural X-chromosome variants; the phenotype and ovarian function vary.
Short stature and hypergonadotrophic ovarian insufficiency are central clues; most people have absent or incomplete spontaneous puberty and infertility.
Bicuspid aortic valve, coarctation, aortic dilatation and hypertension are high-yield cardiovascular associations; dissection can be silent until catastrophic.
Confirm with chromosome analysis; if initial testing is negative but suspicion remains, seek extended-cell or specialist mosaicism testing.
Growth hormone may improve height in eligible children; staged low-dose oestrogen induces puberty and supports bone and uterine development, with progestogen when appropriate.
Pregnancy and egg-donation or IVF need preconception aortic and cardiac risk assessment, specialist maternal-cardiac care and postpartum surveillance.
Y-chromosome material requires urgent specialist discussion of gonadoblastoma risk and gonadal surgery.

First-line investigation

Chromosome analysis, echocardiography and specialist cardiac imaging, gonadotrophins and oestradiol, renal imaging and age-appropriate thyroid, glucose, coeliac, hearing, bone and psychosocial assessment.

Management

Find cardiac and gonadal risk

Arrange chromosome analysis and baseline cardiac, renal and endocrine assessment; urgently escalate sudden chest or back pain, collapse, new neurological symptoms, severe hypertension or absent femoral pulses.^1,2
If Y-chromosome material is identified, refer promptly to genetics and specialist gynaecology or paediatric surgery for gonadoblastoma-risk management.^1,2

Support growth and puberty

Discuss recombinant growth hormone with paediatric endocrinology when current BSPED eligibility criteria are met, with growth and complication monitoring.^6,9
Use specialist-staged low-dose oestrogen induction with gradual increase and add progestogen when clinically appropriate; continue sex-steroid replacement for bone, uterine and general health.^7,5,10

Protect the aorta and pregnancy

Continue lifelong blood-pressure, echocardiographic and cardiac-MRI surveillance, treating coarctation, valve disease, hypertension and aortic changes through an inherited-cardiac team.^2,1,3
Before pregnancy, egg donation or IVF, review aortic anatomy and cardiovascular risk with maternal cardiology; provide an individual plan through pregnancy and postpartum.^8,5,2

Maintain multisystem and person-centred care

Screen and treat thyroid, coeliac, glucose, liver, renal, bone, hearing and visual disease, and provide communication, educational, psychological, social and transition support according to need.^5,1,2

Exam traps

Turner syndrome is the classic chromosomal cause of short stature with primary amenorrhoea and hypergonadotrophic hypogonadism.
Mosaic Turner syndrome may allow spontaneous puberty but does not remove cardiovascular or endocrine surveillance needs.
Coarctation and bicuspid aortic valve are high-yield cardiac associations, but aortic dilatation and hypertension may occur without a murmur.
Y-chromosome material is not reassuring; it raises gonadoblastoma risk and needs specialist management.
Growth hormone is used despite normal GH secretion; oestrogen replacement is needed for pubertal development and bone health, not just fertility.
Normal global intelligence does not exclude visuospatial, executive, social, hearing or mental-health support needs.

Illustrations

Karyotype of 45,XA karyogram showing a single X chromosome with a note that Turner syndrome also includes mosaic and structural X-chromosome variants.No machine-readable author provided. The cat~commonswiki assumed (base, Wikimedia Commons · CC-BY-SA-3.0

Key sources

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.