A genetically inherited sex chromosome abnormality only affecting females. Women with Turner's only have one X chromosome--their genotype is X0. These individuals are short in stature, averaging 4'7" and have distinctive webbed necks (i.e., extra folds of skin). They have exceptionally small breasts and generally lack secondary sexual characteristics. Their ovaries do not develop normally and they do not ovulate. They are in a sense postmenopausal from early childhood and are sterile. In some individuals, there is slight mental retardation. Turner syndrome is rare--current estimates of its frequency range from 1 in 3000 to 1 in 10,000 females.