That the X chromosome contains determinants responsible for statural growth can be deduced from observations that 45,X individuals are short, whereas not all individuals with gonadal dysgenesis are. However, the number and location of statural determinants on the X is uncertain. Moreover, their relationship to X-gonadal determinants and to possible somatic determinants on the Y chromosome have not been elucidated. Certain somatic characteristics of individuals with X-abnormalities, monosomy X, 46,XX gonadal dysgensis, and 46,XY gonadal dysgenesis, were determined. Using methods designed to minimize biases of ascertainment and reporting, the mean height of one sample of 232 45,X individuals had previously been estimated to be 141 ± 0.62 cm; the mean height of 45,X/46,XX individuals is 147 cm (53 cases). Comparisons of various groups indicates that significant differences with respect to height exist. Heterogeneity is detected among 46,X,del(Xq) individuals, but on the basis of available data cannot be correlated with length of Xq deficiency. In other groups, there is little evidence for heterogeneity with respect to height, including XX gonadal dysgenesis, a group for which heterogeneity has been postulated. The following conclusions are drawn: determinants responsible for statural growth are present on Xp; Xq may or may not contain statural determinants; statural determinants on Xp appear to have a different function than any that exist on Xq; and gonadal dysgenesis per se does not result in short stature.
