Gonadal and statural determinants on the X chromosome and their relationship to in vitro studies showing prolonged cell cycles in 45,X; 46,X,del(X)(p11); 46,X,del(X)(q13); and 46,X,del(X)(q22) fibroblasts.

Correlation of clinical features with cytogenetic abnormalities for individuals showing deletions of the X short arm (Xp) or the X long arm (Xq) indicate the following: (1) both Xp and Xq are necessary to assure normal ovarian development, although (2) persisting ovarian function is not infrequently associated with either (del(X)(p11) or del(Xq)(13,21,22, or 24). (3) Ovarian determinants on Xp are localized to region Xp11, but determinants on Xq cannot be precisely localized. (4) Both Xp and Xq contain statural determinants, the former localized to region Xp21 leads to Xpter. Both cell generation time and phases of the cell cycle were studied to test the hypothesis that the short stature, intrauterine growth retardation, and high embryonic lethality of 45,X can be explained on the basis of intrinsic retardation of cell division (i.e., prolonged cell cycle). Cell generation times of four 45,X fibroblast lines were significantly longer than those of for normal diploid lines, a difference accounted for by a prolonged S phase. 46,X,del(X)(p11), 46,X,del(X)(q13), and 46,X,del(X)(q22) lines also showed increased cell generation times when compared to 46,XX lines.