• The disease
• Diagnosis
• Treatment options

Definition

Turner syndrome, named for endocrinologist Henry Turner who described the symptoms in 1938, is due to a genetic abnormality. Girls are normally born with two X chromosomes (46, XX), but in infants born with Turner syndrome, one of the X chromosomes is missing, partially missing or damaged:

• in 55% of cases, there is only one X chromosome (monosomy X: 45, X)
• in 25% of cases, one of the X chromosomes is normal, the other is present but incomplete (deletion);
• In another 20% of cases, the X chromosome is missing in some of their cells, giving what is known as a mosaic pattern, or mosaicism (45, X/ 46, XX).

Symptoms and impact on health

The characteristic features of Turner syndrome are:

• small stature: in 98% of cases, women with Turner syndrome who have not received treatment reach a height of about 145 cm, which is 20 cm shorter than the average. The female growth curve for girls with Turner syndrome deviates from the norm around age four and slows gradually during their growth period;
• ovarian failure with infertility: ovarian development anomalies (ovarian dysgenesis) prevent the onset of puberty in most patients (absence of breast development and menstruation). Although normal in appearance, the genitals remain childish.
• Girls born with Turner syndrome are smaller than average at birth, have a swollen back, hands and feet and a characteristic webbed neck.

Other disorders are associated with Turner syndrome:

• heart abnormalities (hypertension, dilation of the aorta), kidney abnormalities (a single kidney or kidneys joined in a horse shoe shape);
• loss of bone density (osteoporosis), which increases the risk of fractures;
• characteristic facial features (webbed neck) and limbs; swelling of the hands and feet;
• non-insulin-dependent diabetes (i.e. diabetes that is not related to a problem with insulin production);
• hpothyroidism (a thyroid gland abnormality);
• gluten intolerance (coeliac disease);
• obesity;
• ear problems (chronic otitis, hearing loss);
• squint;
• learning difficulties.

Cause

This chromosome anomaly occurs randomly. There are no hereditary or environmental factors that seem to have an influence. Being an older mother is not a known risk factor.

Epidemiology

Turner syndrome is a rare genetic disorder and affects one in 2,500 female births.

Incidence is spread evenly in all populations and in all regions of the globe.