Molecular cytogenetic characterization of 16p11.2 microdeletions with diverse prenatal phenotypes: Four cases report and literature review.

OBJECTIVE: Chromosome 16p11.2 deletions have been recognized as a genetic disorder with well-described postnatal phenotypes. However, the prenatal manifestations are atypical for lacking of enough evidence. CASE REPORT: Four pregnant women underwent amniocentesis for cytogenetic analysis and chromosomal microarray analysis (CMA) because of various indications for prenatal diagnosis: prenatal ultrasound abnormalities (cases 1, 2 and 4) and the childbearing history of cerebral palsy child (case 3). No overlapping phenotypes were observed in cases 1, 2 and 4, which might indicate phenotypic diversities in prenatal phenotypes for 16p11.2 microdeletion. All four fetuses showed normal karyotypic results while CMA identified 0.303-0.916 Mb microdeletions of 16p11.2, encompassing BP2-BP3 and BP4-BP5 regions separately. According to the parental CMA verification, case 1 carried a maternal inherited duplication in the region of Xp22.33 and a de novo deletion in the region of Xp21.1. All parents opted for the termination of pregnancies based upon genetic counselling. CONCLUSION: Our findings enriched the intrauterine phenotypic features of 16p11.2 microdeletions, which would be beneficial for genetic counselling in clinic. In addition, preimplantation genetic testing was recognized as a first-tier approach for such carriers if they intended to conceive again.