Related articles: Turner syndrome
Definition
Turner syndrome is a syndrome associated with the partial or total absence of one of the two X chromosomes in the female sex.
About 50% of women with Turner syndrome have only one X chromosome (karyotype 45, X); the remaining part presents instead an intermediate situation, in which one of the two chromosomes X is partially truncated or is absent only in some cells (mosaicism). Affected individuals have a normal phenotype or have typical features of Turner syndrome. In mosaic forms the symptoms can be more nuanced.
The loss of one of the X chromosomes appears to occur randomly during meiosis (when gametes develop), so the event is not related to maternal or paternal predisposing conditions. Indeed, Turner syndrome is not hereditary, also because affected women are generally infertile.
Most common symptoms and signs *
- Amenorrhea
- blepharoptosis
- clinodactyly
- Coarctation of the aorta
- Learning difficulties
- Difficulty concentrating
- Ovulatory dysfunction
- dysgeusia
- Hydrops Fetal
- Hypercholesterolemia
- Hyperglycemia
- hypertelorism
- Hypertension
- Hearing loss
- infertility
- Lymphedema
- micrognathia
- Misaligned eyes
- Osteoporosis
- Carinated breast
- Reduced vision
- Return of the nipple
- Growth delay
- Mental delay
- Scoliosis
- Telangiectasia
- Brittle nails
- Bicuspid aortic valve
Further indications
The most frequent manifestations of Turner syndrome include short stature, swollen hands and feet (lymphedema), broad chest with widely spaced and recessed nipples. An increase in the angle of valgus is observed in the elbow. Other anomalies are the low hairline, the large and low-implanted ears, the skin folds in the back of the neck, the eyelid ptosis, the hypoplasia of the nails and the shortening of the IV finger of the hand or of the foot. In 90% of females, gonadal dysgenesis occurs: the ovaries are replaced by bilateral striations of fibrous stroma, unable to develop ovules. This leads to ovarian failure and problems in triggering normal pubertal development. Menstruation may persist for a limited period of time (primary amenorrhea), while secondary sexual characteristics develop only partially or are absent.
Turner syndrome causes other medical problems such as heart defects (in particular, coarctation of the aorta and bicuspid aortic valve), renal malformations, strabismus, hypermetropia, scoliosis and hearing problems. Thyroiditis and celiac disease are more frequent than the general population and there is a propensity to develop diabetes. Hypertension and osteoporosis often occur as we age. In Turner syndrome mental retardation is rare, but learning disabilities are common.
The diagnosis is confirmed by the finding of a cytogenetic anomaly of the X chromosome by karyotype analysis. Treatment depends on the manifestations and may include surgery for congenital heart disease and drug therapy with growth hormone and replacement estrogen.
