[Genetic diagnosis and noninvasive prenatal testing of a family with Williams-Beuren syndrome].

OBJECTIVE

To explore the genetic basis of a fetus with ventricular septal defect (VSD) by using modified noninvasive prenatal testing (NIPT) for the detection of microdeletion syndromes.

METHODS

Chromosomal karyotypes of the fetus and its parents were analyzed by G-banding technique. Next generation sequencing (NGS) was used to detect genomic copy number variations (CNVs) in cell-free fetal DNA. The results were verified by fluorescence in situ hybridization (FISH).

RESULTS

The fetus and its parents all had a normal karyotype at 320-400 band level. NGS revealed a deletion of 1.30 Mb at 7q11.23 in the fetus, with a 93% overlap with that of Williams-Beuren syndrome (WBS). The father also had a deletion of 1.42 Mb at 7q11.23, with a 99% overlap with that of WBS. Modified NIPT also detected the 1.30 Mb deletion at 7q11.23 in the fetus. The result of FISH has confirmed the above results.

CONCLUSION

It is necessary to carry out genetic testing on fetuses with VSD. NGS can detect fetal microdeletion syndromes and help to trace their parental origin. The modified NIPT for fetal chromosomal microdeletions/microduplication syndromes is highly accurate.