Parental origin and mechanisms of formation of triploidy: a study of 25 cases

Abstract

Triploidy is one of the most frequently observed chromosome abnormalities in spontaneous abortions in humans. The parental origin of the additional chromosome set is known to have a major impact on the phenotype of the foetuses and to result in differences in size and structure of the placenta. Early studies based on cytogenetic polymorphisms indicated a preponderant diandric origin of the triploidies; such detection method, however, is known to be prone to error. Other studies revealed a predominant digynic origin in cases with longer intrauterine survival. It is now thought that, to some extent, a detection bias in favour of cases with associated partial hydatidiform moles may account for the high incidences of diandric cases reported in some studies. Furthermore, depending on the gestational age of the cases analysed there may indeed be differences in the proportion of diandric and digynic triploidies. We investigated the parental origin and mechanisms of formation of triploidy in a group of 25 probands with gestational ages ranging from 8 to 37 weeks. DNA samples were extracted from foetal material and from blood samples of the parents, and were analysed using microsatellite markers. The parental origin of the triploidies was found to be maternal in 20 cases and paternal in 5. Regarding the digynic cases, an error at meiosis I was inferred in 10 cases, whereas in the other half an error occurred at meiosis II. All five diandric cases included in this study were found to be due to dispermy. No significant differences in the average maternal ages were found amongst the different subgroups of patients. European Journal of Human Genetics (2000) 8, 911-917.

X inactivation in triploidy and trisomy: the search for autosomal transfactors that choose the active X

“…In addition, because the unbalanced translocations were associated with congenital malformations and were inherited from a phenotypically normal balanced translocation carrier, it is likely that the extra copy of the triplicated 9 McFadden et al, 10,11 Baumer et al, 12 Daniel et al 13 and Kajii et al 14 Triploidy, trisomy and choice of active X BR Migeon et al segment was expressed. Direct duplications in males and females were also mapped but were not used for exclusions, as both copies are on the same chromosome and might function as one copy rather than two and might be subject to position effects.…”

Parental origin of the two additional haploid sets of chromosomes in an embryo with tetraploidy

“…Determination of the parental origin and time of formation of the tetraploidy was performed using basically the same procedure previously published for the investigation of cases with triploidy (Baumer et al, 2000). Briefly, twenty microsatellite markers mapping to the pericentromeric regions of eighteen different chromosomes (Research Genetics, Huntsville, AL, USA) were investigated by PCR.…”

Triploid Colubrid Snake Provides Insight into the Mechanism of Sex Determination in Advanced Snakes

“…Spontaneous triploidy caused by dispermic fertilization of an egg or abnormal meiosis during gametogenesis was reported in sauropsids including birds [Stenberg and Saura, 2013]. In the majority of cases, spontaneous triploidy in amniotes leads to death at a young age, and only a small percentage of triploids reach maturity [Bonaminio and Fechheimer, 1993;Baumer et al, 2000;Trukhina and Smirnov, 2014]. Adult triploid ZZZ and ZZW chicken and triploid ZZZ zebra finches usually develop a male phenotype often with abnormal gonads, although ovotestes were also reported [Ohno et al, 1963].…”