Turner Syndrome

A syndrome of defective gonadal development in phenotypic women with a karyotype of sex chromosome monosomy (45,X or 45,XO), associated with the loss of a sex chromosome X or Y. Patients generally are of short stature with undifferentiated (streak) gonads, sexual infantilism (hypogonadism), webbing of the neck, cubitus valgus, elevated gonadotropins and decreased estradiol level in blood. Studies of Turner Syndrome and its variants have contributed significantly to the understanding of sex differentiation. noonan syndrome bears similarity to this disorder; however, it also occurs in males, has normal karyotype, and is inherited as an autosomal dominant. This syndrome that was originally observed by Ullrich, and designated as identical to turner syndrome, related the webbing of the neck, loose skin and other anomalies of the syndrome to accumulation of fluid in the embryo starting at the head and dispersing to the extremities (as observed by Bonnevie in mice). Commonly observed at birth in Turner Syndrome and noonan syndrome; edema of the extremities usually recedes by one year and is an early sign of Turner syndrome, especially in female neonates.