Case Report: A novel compound heterozygosity of the EVC 2 gene identified in a Chinese pedigree with congenital heart defect

Abstract

Background: Congenital heart defects (CHDs) represent the leading cause of neonatal mortality among congenital abnormalities. Genetic factors, such as EVC2 gene mutations and other genetic alterations, constitute a major cause of CHD. Thus, determining the genetic etiology of fetal CHDs is crucial for optimizing pregnancy management and informing future reproductive decisions.

Case presentation: Here, we describe a male fetus with complex CHD who was diagnosed at 25 weeks of gestation, delivered at full term, and died prematurely within a month due to heart failure. The cardiac abnormalities observed included an atrial septal defect developing from a patent foramen ovale, mitral valve regurgitation, dilated right ventricle and left atrium, aortic stenosis, and aortic arch dysplasia. Novel compound heterozygosity of the EVC2 gene, including a non-sense mutation (p.W828Ter) and two cis missense mutations (p.E87G and p.S217C), was identified by prenatal trio-whole-exome sequencing of amniotic fluid, followed by validation using Sanger sequencing. This novel EVC2 genotype was supposed to potentially affect fetal cardiac development, given the variable clinical heterogeneity of the EVC2 mutation-associated phenotype. This case represents the first identification of the EVC2 p.E87G and p.S217C, and the isolated CHD without visible skeletal dysplasia is an important feature of our case.

Conclusions: Our study expands the genotypic and phenotypic spectra of the EVC2 gene. We recommend including the EVC2 gene in preconception carrier screening and prenatal diagnosis for CHDs.

Keywords: EVC2; Ellis–van Creveld syndrome; case report; congenital heart defect; fetus; neonate.

Figure 1

Imaging examination results. (A,C) Echocardiography performed during the fetal period (25 weeks pregnant) and neonatal period, respectively, showed the coarctation of the aortic arch (marked with an arrowhead). (B) The fetus exhibited pulmonary and aortic blood flow incongruity with an increased vessel ratio. (D) Neonatal imaging showing a patent ductus arteriosus aneurysm (marked with an arrowhead) and a bidirectional arterial shunt. (E) Digital x-ray imaging did n't show any obvious developmental abnormalities of the sternum, ribs, or spine.

Figure 2

Family pedigree and Sanger sequencing validation of three EVC2 mutations. (A) The family pedigree. The cause of the last three miscarriages remains unknown due to the absence of preserved samples for further detection. (B–D) Chromas showing the mutation in the family. The position of EVC2 p.W828*, p.S217C, and p. E87G is marked with a black box.