Clinical features: The clinical diagnosis of Turner syndrome may be considered in a newborn girl with puffy feet (lymphoedema) and congenital heart disease. More commonly, however, the diagnosis is made only later during the investigation of short stature or primary amenorrhoea (absence of periods). Girls with Turner syndrome are usually short in height, with no growth spurt at puberty. Growth hormone may be given both to improve the velocity of growth and the final adult height. Turner syndrome also prevents the ovaries from developing properly and because the ovaries are responsible for making the hormones that control breast growth and menstruation, puberty will not occur unless oestrogen replacement therapy is given. Oestrogen replacement therapy is also important for the maintenance of healthy bones. Nearly all women with Turner syndrome are infertile, but there are assisted reproductive technologies available that may enable a woman with Turner syndrome to become pregnant, and expert advice regarding this should be sought when appropriate. Intelligence and lifespan are unaffected.
Incidence: The overall birth incidence is 1 in 5,000 females. The frequency at conception is much higher as over 99% of fetuses with Turner Syndrome miscarry.
Chromosome: result: 45,X in 50% of cases, mosaicism in 24%. Several other karyotypes involving structural anomalies of an X chromosome account for the remainder.
Recurrence risk: The risk of recurrence does not appear to be increased above the general population risk.
Use this set of presentation slides to explain the genetics of Turner syndrome (45,X).