Turner Syndrome

Turner syndrome is a sex-chromosome condition affecting individuals with a typically female pattern of development. It results from complete or partial absence or alteration of one X chromosome. The chromosome pattern is established at conception and does not progressively worsen, but its effects become visible at different stages of childhood. Reduced X-chromosome gene dosage affects growth and ovarian development. The result is commonly short stature and gonadal insufficiency, with delayed or absent spontaneous puberty. Low estrogen exposure also reduces the normal accumulation of bone mineral, increasing the risk of low bone density and fractures. Associated differences in cardiovascular, renal, auditory, thyroid, and metabolic systems explain why care extends beyond height and puberty. Mosaic Turner syndrome contains more than one cell line, so the clinical picture can be subtle. A child may have some spontaneous pubertal development or menstruation and still have Turner syndrome. A relatively well child with a normal newborn examination is not necessarily unaffected.