Mammalian spermiogenesis is marked by the initial disruption of the nuclear-histone-DNA complex by the transition proteins for ultimate replacement with protamines. The genes for three of these low molecular weight basic nuclear proteins exist as a single linear array of PRM1, PRM2, and TNP2 on human chromosome 16p13.2. To begin to address the mechanism governing their transcriptional potentiation, a region of approximately 40 kilo-bases of the human genome encompassing these genes was introduced into the germ line of mice. Fluorescence in situ hybridization and Southern analysis showed that this segment of the human genome integrated into independent chromosomal sites while maintaining its fidelity. Transcript analysis demonstrated that the expression of the endogenous mouse protamine Prm1 and Prm2 genes as well as the mouse transition protein Tnp2 gene were expressed along with their human transgene counterparts. The pattern of expression of these transgenic human genes within this multigenic cluster faithfully represented that observed in vivo. In addition, all members of this transgenic gene cluster were expressed in proportions similar to those in human testis. Copy number-dependent and position-independent expression of the transgenic construct demonstrated that the corresponding biological locus was contained within this segment of the human genome. Furthermore, DNase I sensitivity established that in sperm the human PRM1-->PRM2-->TNP2 genic domain was contained as an approximately 28.5-kilobase contiguous segment bounded by an array of nuclear matrix associated topoisomerase II consensus sites. This is the first description of a multigenic male gamete-specific domain as a fundamental gene regulatory unit. A model of haploid-specific gene determination is presented.

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We performed chorionic villus samplings (CVS) in 795 cases in the first trimester during a 13-month period. Of these 35 were found to have a blighted ovum or missed abortion prior to the procedure. Nineteen women consented to have CVS. Ultrasonographic and cytogenetic findings in these 19 pregnancies were correlated. Expected gestational age was determined by last menstrual period. Observed gestational age was determined by crown rump length (CRL) (12 pregnancies) or gestational sac (GS) (7 pregnancies without fetal pole). The differences in days between the estimated and observed gestational ages was determined for each pregnancy. In all 19 CVS samples cytogenetic diagnosis documented aneuploidy. Ten cases had chromosome abnormalities virtually always lethal in the embryonic period (group I). Nine pregnancies had defects with moderate potential for fetal viability (group II). Gestations with low viability potential (group I) had estimated minus observed gestational age discrepancies (23.4 +/- 8.3 days) significantly greater than gestations with moderate viability potential (group II) (8.9 +/- 4.3 days) (P less than .001). The absence of a fetal pole was more common in group I. CVS in pregnancies with missed abortion or blighted ovum is feasible and has a high likelihood of documenting aneuploidy. Furthermore, the more severe the anomaly the more likely there will be very early fetal demise or intrauterine growth retardation.

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