Genetic testing and analysis of 2 cases of trisomy 11 mosaicism / 南方医科大学学报

Trisomy 11 mosaicism is clinically rare, for which making diagnostic and treatment decisions can be challenging. In this study, we used noninvasive prenatal testing, chromosome karyotype analysis, chromosome microarray analysis, copy number variation sequencing and fluorescence in situ hybridization for detecting trisomy 11 mosaicism in two cases and provided them with genetic counseling. In one of the cases, the fetus with confined placental mosaicism trisomy 11 presented with severe growth restriction and a placental mosaic level of 44%, and pregnancy was terminated at 25+3 weeks of gestation. In the other case with true low-level fetal mosaicism of trisomy 11, the pregnancy continued after exclusion of the possibility of uniparental disomy and structural abnormalities and careful prenatal counseling. The newborn was followed up for more than one year, and no abnormality was found. Noninvasive prenatal testing is capable of detecting chromosomal mosaicism but may cause missed diagnosis of true fetal mosaicism. For cases with positive noninvasive prenatal testing but a normal karyotype of the fetus, care should be taken in prenatal counseling and pregnancy management.

Intrauterine growth restriction (IUGR) associated with confined placental mosaicism of ring chromsome 15

The present report describes a case that showed a normal fetal karyotype in an antenatal genetic study but an abnormal placental karyotype of 46,XX,r(15) on postnatal examination. The pregnancy was complicated by fetal nuchal translucency in the first trimester and intrauterine growth restriction in the second and third trimesters. A 1780 gm female baby was born after 40 weeks of gestation, but died of respiratory distress and sepsis on the 10th day of life. Our case was unique in that the placental chromosomal aberration was a structural abnormality instead of a numerical aberration that is seen in most reported cases of confined placental mosaicism.