A novel NOTCH1 missense variant in two fetuses with a non-syndromic conotruncal heart defect from a single family

We describe two fetuses with conotruncal heart defects (CTDs) (persistent truncus arteriosus and pulmonary atresia/ventricular septal defect, respectively) in a Chinese family whose parents were both healthy. Testing was performed to identify any underlying genetic cause.

Genomic DNA was extracted from the peripheral blood of the proband's parents and the skeletal muscle tissue of the two aborted fetuses for genetic testing.

A heterozygous likely pathogenic missense variant, c.1724G〉C (:p.Cys575Ser), in the NOTCH1 gene (NM_017617.5) was detected in the two affected fetuses but not in the parents, and the next generation sequencing test of the proband's father showed a normal result. It is therefore presumed to result from germline mosaicism in the proband's mother or, less likely, is a recurrent de novo variant in the fetuses.

This is the first description of fetal non-syndromic CTD caused by a variant in NOTCH1. This report not only expands the gene variant spectrum of CTDs, but also emphasizes the importance of NOTCH1 testing when a fetal of CTD is detected.