The unprecedented recurrent diploid/tetraploid mosaicism of trisomy‐18 (mixoploidy; 4n+18/2n+18): Clinical report

Abstract

We report on a 32-year-old woman who presented at gestational age of 14 weeks. During ultrasonographic examination, we discovered that her fetus had several important abnormalities, including a cystic hygroma, craniofacial defects (low-set ears, broad nose), heart defects (single atrium, single ventricle), agenesis of corpus callosum, limb defects (clenched hands, pes equinovarus). Chorionic villus sampling and karyotyping revealed diploid/tetraploid mosaicism with trisomy 18 (mixoploidy; 4n+18/2n+18). Her second pregnancy was terminated because of the same clinical manifestations 1 year prior. Her first pregnancy resulted in the birth of an entirely healthy boy. As far as know, no other similar case has been presented in the literature.

Tetraploid–diploid mosaicism in a patient with pigmentary anomalies of hair and skin: a new dermatologic feature

“…Complete tetraploidy can be defined as four chromosome sets in one cell and usually occurs secondary to nondisjunction during the first mitosis in a zygote . It has been reported in spontaneous abortions, but is rare in live‐born infants .…”