Abstract
PurposeTo establish the distribution of diandric and digynic triploidy depending on gestational age.Methods107 triploid samples tested prospectively in a single genetic department during a four-year period were analyzed for parental origin of triploidy by Quantitative Fluorescent Polymerase Chain Reaction (QF-PCR) (n=95) with the use of matching parental samples or by MS-MLPA (n=12), when parental samples were unavailable. Tested pregnancies were divided into three subgroups with regard to the gestational age at spontaneous pregnancy loss: <11 gestational weeks, 11–14 gestational weeks, and >14 gestational weeks.ResultsDiandric triploidy constituted overall 44.9% (46.5% in samples miscarried <11 gestational weeks, 64.3% in samples miscarried between 11 and 14 gestational weeks, and 27.8% in pregnancies which survived >14 gestational weeks).ConclusionsThe distribution of diandric and digynic triploidy depends on gestational age. The majority of diandric triploid pregnancies is lost in the first trimester of pregnancy. In the second trimester, diandric cases are at least twice less frequent than digynic ones.
Highlights
Triploidy is a frequent genetic aberration affecting around 1– 2% of all conceptions [1]
Even though conventional karyotyping does not identify the parental origin of triploidy, the majority of cases diagnosed beyond 11 gestational weeks may be accurately classified as diandric or digynic based on ultrasound assessment [6, 7]
If miscarried at earlier developmental stages, further molecular testing is needed to establish the parental origin of triploid pregnancy, which is rarely conducted in routine practice [8]
Summary
Triploidy is a frequent genetic aberration affecting around 1– 2% of all conceptions [1]. The prevalence of triploidy decreases dramatically with gestational age as the majority of cases is miscarried in early pregnancy [2, 3]. Triploidy results from an extra haploid set of chromosomes of paternal (diandric) or maternal (digynic) origin. In case of more common karyotypes 69,XXX and 69,XXY, the extra chromosomal set may be of paternal or maternal origin and further investigations are necessary to detect parental contribution. Even though conventional karyotyping does not identify the parental origin of triploidy, the majority of cases diagnosed beyond 11 gestational weeks may be accurately classified as diandric or digynic based on ultrasound assessment [6, 7]. If miscarried at earlier developmental stages, further molecular testing is needed to establish the parental origin of triploid pregnancy, which is rarely conducted in routine practice [8]. The distribution of diandric and digynic triploidy with regard to gestational age has not been accurately established to date
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