Turner syndrome and differences of sex development (DSD) at generalist depth

Also known as Turner syndrome · 45,X · Gonadal dysgenesis · Differences of sex development · DSD · Congenital adrenal hyperplasia · Androgen insensitivity · Ambiguous genitalia

Exam-exhaustive FRANZCOG foundation on Turner syndrome (45,X and mosaics, the phenotype, SHOX haploinsufficiency and short stature, gonadal dysgenesis and premature ovarian insufficiency, the cardiac and renal associations, and the timing of growth hormone and oestrogen replacement) together with a generalist-depth DSD overview — the 2006 consensus classification, the urgent exclusion of salt-wasting congenital adrenal hyperplasia in the newborn with ambiguous genitalia, androgen insensitivity, and the initial evaluation and multidisciplinary care pathway. ANZ-primary, globally tagged to MRCOG, ABOG, FRCSC and MRCPI.

medium12 referencesUpdated 27 July 202613 min readVerification in progress

Practise this topic

8 MCQs

One-line fellowship answer

Turner syndrome is the syndrome in females caused by complete or partial absence of one X chromosome — from classic 45,X to mosaics and structural X abnormalities — driven by SHOX haploinsufficiency (short stature), gonadal dysgenesis (premature ovarian insufficiency), and a cardiovascular phenotype (bicuspid aortic valve, coarctation, aortic dissection) that demands lifelong surveillance and clearance before pregnancy. A newborn with ambiguous genitalia is a differences of sex development (DSD) presentation under the 2006 consensus classification (sex chromosome DSD, 46,XX DSD, 46,XY DSD) — and the immediate generalist priority is to exclude salt-wasting congenital adrenal hyperplasia with urgent electrolytes and 17-hydroxyprogesterone, karyotype the child, and convene the multidisciplinary team before any sex is assigned.^[1]^[6]^[8]

A 14-year-old sits in your adolescent clinic with primary amenorrhoea and a height three standard deviations below the mean. Across town, a newborn with ambiguous genitalia is being examined by the neonatal SHO. Both answers live on the same page: the chromosomal blueprint, the gonad, and the careful, multidisciplinary, lifelong plan. The generalist's job is recognition, stabilisation and referral — not definitive subspecialty management.^[1]^[9]

Overview and definition

Turner syndrome (TS) is the clinical syndrome resulting from complete or partial absence of one X chromosome in a female — the most common sex-chromosome aneuploidy compatible with life. It affects multiple organs across the lifespan, mandating structured multidisciplinary care.^[1]

Why this matters — Turner in numbers

50 per 100,000Female prevalenceGravholt 2024 guideline — quote the guideline figure

45,X and mosaicsKaryotype splitclassic 45,X plus mosaic and structural X variants

commonCardiovascular abnormalitySybert 1998: over half of evaluated patients affected

driven by cardiovascularAdult excess mortalityaortic dissection is the feared, preventable killer

^[1] ^[2]

Differences (or disorders) of sex development (DSD) are congenital conditions in which chromosomal, gonadal or anatomical sex is atypical. The 2006 International Consensus Conference on Intersex replaced pejorative older terms (intersex, pseudohermaphroditism) with a karyotype-anchored classification and reframed the whole field around the multidisciplinary team and the family.^[6]^[11]

References12Show

[1]Gravholt CH, Andersen NH, Christin-Maitre S, et al. Clinical practice guidelines for the care of girls and women with Turner syndrome. Eur J Endocrinol, 2024.PMID 38748847
[2]Sybert VP Cardiovascular malformations and complications in Turner syndrome. Pediatrics, 1998.PMID 9417175
[3]Mortensen KH, Wen J, Erlandsen M, et al. Aortic growth rates are not increased in Turner syndrome: a prospective CMR study. Eur Heart J Cardiovasc Imaging, 2019.PMID 31329837
[4]Wen J, Trolle C, Viuff MH, et al. Impaired aortic distensibility and elevated central blood pressure in Turner Syndrome: a cardiovascular magnetic resonance study. J Cardiovasc Magn Reson, 2018.PMID 30541571
[5]Grewal J, Valente AM Cardiovascular outcomes of pregnancy in Turner syndrome. Heart, 2021.PMID 32669396
[6]Lee PA, Houk CP, Ahmed SF, Hughes IA; International Consensus Conference on Intersex Consensus statement on management of intersex disorders. International Consensus Conference on Intersex. Pediatrics, 2006.PMID 16882788
[7]Lee PA, Nordenström A, Houk CP, et al. Global Disorders of Sex Development Update since 2006: Perceptions, Approach and Care. Horm Res Paediatr, 2016.PMID 26820577
[8]Speiser PW, Arlt W, Auchus RJ, et al. Congenital Adrenal Hyperplasia Due to Steroid 21-Hydroxylase Deficiency: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab, 2018.PMID 30272171
[9]Lucas-Herald AK, Rodie ME, Ahmed SF Update on the management of a newborn with a suspected difference of sex development. Arch Dis Child, 2022.PMID 34772663
[10]Claahsen-van der Grinten HL, Speiser PW, Ahmed SF, et al. Congenital Adrenal Hyperplasia-Current Insights in Pathophysiology, Diagnostics, and Management. Endocr Rev, 2022.PMID 33961029
[11]Hughes IA, Houk C, Ahmed SF, Lee PA Consensus statement on management of intersex disorders. J Pediatr Urol, 2006.PMID 18947601
[12]Panay N, Anderson RA, Bennie A, et al. Evidence-based guideline: Premature Ovarian Insufficiency. Fertil Steril, 2025.PMID 39652037