Turner syndrome (45,XO) is a chromosomal anomaly in female sex with X chromosome fully or partially missing. Incidence: 1 per 2,000-2,500 female births. Turkey estimates 200-250 new cases annually. Diagnosis is simple (karyotype), but it often comes late — missed opportunities are common.
History + epidemiology
- 1938: Henry H. Turner first clinical description (7 patients: short stature
- sexual development insufficiency)
- 1959: Ford et al. identified the 45,XO karyotype
- 2000+: SHOX gene located on X chromosome — main driver of short stature
Chromosomal causes
45,XO classical (50% of cases)
- All cells missing one X chromosome
- Most severe clinical picture
Mosaic (45,X / 46,XX) (30%)
- Some cells 45, others 46
- Clinical picture may be milder
- Spontaneous menses possible in some cases
Structural X anomalies (20%)
- X isochromosome, ring X, partial deletions
- Karyotype + FISH analysis required
Clinical features
Newborn period
- Lymphedema (hand-foot swelling)
- Webbed neck
- Low posterior hairline
- Wide chest + spaced nipples
- Congenital heart anomalies (aortic coarctation, bicuspid aortic valve — 30%)
- Renal anomalies (horseshoe kidney — 30%)
Childhood
- Short stature (most common diagnostic finding)
- Untreated adult height: 143 cm (Turkish population)
- Percentile drop visible from age 2
- Families often think "she'll start later" — diagnosis delayed to 5-6 yrs
Adolescence
- Gonadal dysgenesis — streak ovaries, no estrogen
- Delayed or absent puberty
- Secondary amenorrhea
- Infertility (95% of cases)
Adulthood
- Low bone mineral density → osteoporosis
- High type 2 diabetes risk
- Autoimmune thyroiditis (30%)
- Hearing loss (middle ear anomalies)
Diagnostic algorithm
Triggers — order karyotype
- Newborn lymphedema
- Marked short stature over age 2 (below p3)
- Delayed puberty + short stature (12+ yrs)
- Recurrent otitis media + hearing loss
- Congenital heart anomaly (girl infants screened)
Karyotype analysis
- Peripheral blood lymphocytes (≥30 cells)
- 45,X finding diagnostic
- If mosaicism suspected: >100 cells + extra tissue (skin, oral mucosa)
Post-diagnosis annual screening
- Thyroid (TSH, anti-TPO) — autoimmune comorbidity
- Glucose, HbA1c — diabetes risk
- Liver enzymes
- Lipid panel
- Bone mineral density (DEXA, age 5+)
- Hearing test
- Echo + ECG (cardiac follow-up)
Treatment: GH + estrogen
Growth hormone (GH) therapy
- Start at 4-6 yrs recommended
- Dose: 0.045-0.050 mg/kg/day (higher than standard pediatric)
- Daily subcutaneous injection
- Goal: add +8-12 cm to adult height (143 → ~153)
- Covered by Turkey's SGK
GH success depends on:
- Early start (4-6 yr ideal)
- Dose titration (IGF-1 monitored)
- Compliance (daily injection)
Estrogen replacement therapy
- Start at 11-12 yrs (puberty timed with peers)
- Transdermal (gel or patch) preferred
- Low-dose start, titrate to adult dose over 2 yrs
- 14-15 yrs: progesterone added for menstrual cycle
GH + estrogen combination is standard for Turner; not alternative.
Surgery
- Y chromosome mosaic (45,X/46,XY) → gonadoblastoma risk → prophylactic gonadectomy
- Congenital heart anomaly → cardiovascular surgery if needed
Fertility
- 95% infertility — ovarian dysgenesis
- IVF + donor eggs allows pregnancy
- 5-10% of mosaic cases conceive spontaneously (high miscarriage risk)
- Autologous fertility preservation not possible pre-puberty
- New hope: artificial follicle generation from 45,X individuals (experimental)
Cognitive + psychosocial
- General IQ normal (average)
- Visuospatial weakness (math, engineering harder)
- Social skills sometimes delayed
- Adolescent self-esteem + depression risk increased
- Pediatric psychology + social support standard
Turkish Turner Syndrome Association
Active patient and family organization. Annual education events, endocrinology specialist guidance, educational materials. https://turner.org.tr
FAQ
Can my child have Turner if their height is normal?
Mosaic cases may have normal height. If suspected, karyotype is needed. Normal height but absent menses, or congenital cardiac/renal anomaly → karyotype should be considered.
Can a Turner-syndrome child attend regular school?
Yes — IQ is normal. Just extra support in visuospatial subjects may help. Social support + adolescent psychology standard.
How effective is GH therapy?
Started early, adult height improves by 8-15 cm. Therapy lasts 10-12 yrs. Family + child compliance is critical. Long-acting weekly forms emerging.
When should estrogen therapy start?
11-12 yrs to time puberty with peers. Earlier accelerates epiphyseal closure, reducing height gain. Endocrinology-supervised.
Bottom line
Turner syndrome is largely manageable with early diagnosis + multidisciplinary follow-up. Short stature + secondary amenorrhea + congenital cardiac anomaly in a girl → karyotype is standard. For systematic growth tracking, sign up free; if percentile deviation appears, consult pediatrician + endocrinology.