De novo c.2455C>T mutation of NPR2 gene in a fetus with shortened long bones and a ventricular septal defect conceived by a mother with a fragile site at 16q22.1 and a father with a rare heterochromatic variant of chromosome 4 from Vietnam

Abstract

Background: A heterozygous natriuretic peptide receptor 2 (NPR2) gene c.2455C>T mutation was identified as a cause of familial idiopathic short stature (ISS). Only two cases with this mutation were reported previously, and the probands with ISS had no organ system defects.

Methods: Next-generation sequencing (NGS) was performed on an amniotic fluid DNA sample of a fetus with shortened long bones and a small ventricular septal defect detected by an obstetric ultrasound examination. The pathogenic variant of the fetus was confirmed by Sanger sequencing. Sanger sequencing, G-banded, and C-banded karyotyping of the fetus's parents were subsequently performed.

Results: A de novo NPR2 gene c.2455C>T, p.(Arg819Cys) mutation was identified in the fetus. No microdeletion or microduplication was identified in the fetus by copy number variation sequencing with a maximum resolution of 400 kb. The two previous miscarriages experienced by the fetus's parents were interpreted as a result of chromosomal aberrations, including a maternal fragile site at 16q22.1 and a rare paternal variant involving in a large G-band-positive and C-band-positive block of paracentric heterochromatin of chromosome 4p.

Conclusion: This report provides clinical signs of a de novo heterozygous NPR2 gene c.2455C>T mutation in the fetus and shows paternal chromosomal aberrations causing repeated pregnancy loss.

Keywords: NPR2 gene c.2455C>T; fragile site at 16q22.1; repeated pregnancy loss; shortened long bones; variant of paracentric heterochromatin of chromosome 4p.