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

Abstract

Aims: 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.

Materials and methods: 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.

Results: 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.

Conclusion: 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.