- Turner syndrome: monosomic condition of the X chromosome, found only in phenotypic females; karyotype 45,X (45,XO).
Aetiology and Karyotype
- Caused by nondisjunction of the X chromosome during meiosis, giving a 45,XO chromosomal complement in somatic cells.
- In 75% of patients, the single retained X chromosome is of maternal origin.
Clinical Features
- Phenotype: short stature; webbed neck; shield chest with pinpoint nipples; bilateral cubitus valgus; low-set ears; infantile external genitalia; gonadal dysgenesis with amenorrhoea; coarctation of aorta.
external phenotype, clinical photograph External phenotype, clinical photograph.