First-trimester non-invasive prenatal diagnosis of triploidy

Abstract

We report a case of fetal triploidy in which fetal nucleated red blood cells were isolated from the maternal peripheral circulation at 12 weeks' gestation. FISH analysis with X and Y specific probes revealed three hybridization signals for the X chromosomes in 14 cells. The karyotype as established after CVS was shown to be 69,XXX. Two other non-invasive first-trimester screening methods were also evaluated. The serum markers pregnancy-associated plasma protein A (PAPP-A) and the free β-chain of chorionic gonadotrophin (free β-hCG) were both shown to be decreased in the same blood sample. An enlarged nuchal translucency (5 mm ≥ 95th centile) was seen at 13 + 2 weeks of gestation.