A cytogenetic and molecular study of a series of 45,X fetuses and their parents

Turner's syndrome: a behavioral and cytogenetic study

This study focused on the behavioral and cytogenetic aspects of Turner's syndrome. We evaluated the behavioral scores by ESPQ, HSPQ, and TAMAI tests. In the cytogenetic study, six different variables were defined by a chromosome image analysis computer system (Applied Imagine) that assessed changes in band organization and the measurement of mean optical density (MOD) in six G-bands (Xp21, Xq12, Xq21, Xq23, Xq25, Xq27). We studied 33 females with Turner's syndrome and compared them with 30 females individually matched for normal karyotype, short stature, age, and education. Significant differences were found between the two groups.

Molecular studies of parental origin and mosaicism in 45,X conceptuses

The present report summarizes molecular studies of parental origin and sex chromosome mosaicism in forty-one 45,X conceptuses, consisting of 29 spontaneous abortions and 12 liveborn individuals with Turner syndrome. Our studies indicate that most 45,X conceptuses have a single, maternally derived X chromosome, regardless of whether the conceptus is liveborn or spontaneously aborted. In studies of mosaicism, our identification of X- and Y-chromosome mosaics among 45,X spontaneous abortions indicates that mosaicism does not ensure survival to term of 45,X fetuses. However, the incidence of sex chromosome mosaicism is substantially higher in liveborn than in aborted 45,X conceptuses, indicating that the presence of a second cell line increases the likelihood of survival to term.

Molecular study of 45,X conceptuses: correlation with clinical findings

The parental origin of the single X in 45 cases (40 liveborns and 5 fetuses) with a 45,X karyotype was studied using polymorphic DNA probes. The single X was paternal in origin (Xp) in 10 cases (22.2%) and maternal (Xm) in 35 cases (77.8%). Y chromosome material was detected in 1 out of the 35 cases with a 45,Xm constitution. Analysis of parental ages and clinical data of the patients with respect to the origin of the single X revealed no significant differences between the origins.

Survival of fetuses with 45,X: an instructive case and an hypothesis

The high (greater than 95%) fetal loss rate of 45,X embryos and fetuses has led to the suggestion that fetal survival with this karyotype requires the presence of mosaicism. However, in many instances, even given a "mild Ullrich-Turner syndrome" phenotype, mosaicism is not detected. In a pregnancy studied for advanced maternal age, CVS cultured cells showed 65% 45,X and 35% 46,X,r(X). After termination, 2 fetal tissues showed 95% 45,X cells. It is suggested that infants with the 45,X karyotype likely had mosaicism for a structurally abnormal X or Y chromosome during embryogenesis, but the abnormal cell line disappeared prior to birth.