ABSTRACT
Since its recognition as a clinically distinct disorder (Turner, 1938), and discovery of an association with monosomy X (Ford, Jones, Polani, de Almeida, & Briggs, 1959), the Turner syndrome has become one of the most widely recognized and investigated syndromes. It is less common at birth than other conditions with sex chromosomal abnormalities, occurring in approximately 1:2,000 to 1:5,000 live female births. This has been attributed to a much greater prenatal mortality rate than cytogenetically normal embryos, or those with additional X or Y chromosomes (47,XXX, 47,XXY, and 47,XYY) (Hook & Warburton 1983). Half of first-trimester spontaneous abortuses have abnormal karyotypes, and nearly 20% of those are 45, X or have other cytogenetic variants found in individuals with the Turner phenotype. The reduction in viability of 45,X is thought to result from vascular abnormalities and gross fluid imbalance (Canki, Warburton, & Byrne, 1988), as well as generalized growth retardation, rather than to the effects of specific malformations. It has therefore been difficult for individual investigators to accumulate enough patients with the Turner syndrome for systematic, controlled studies of its postnatal manifestations.
