Novel Functional FOXC1 Variants in Familial and Sporadic Atrial Septal Defect

Abstract

ObjectiveAtrial septal defect (ASD) is one of the most common forms of congenital heart disease. Genetic defects play important roles in the pathogenesis of ASD but are complex and unclear. This study tries to discover the genetic pathogenesis in familial and sporadic ASD patients.MethodsIn Stage I, in a family with 30 members whole exome sequencing was performed in 4 ASD patients and the identified genetic variants were screened in the rest of the family members. In Stage II, 335 unrelated sporadic and isolated ASD patients were enrolled to test whether the genetic variants were involved in these patients. In Stage III, biological functions of the variants were elucidated at the cellular level and the CRISPR/Cas9 was used to construct variant‐specific mutant mice in order to observe the abnormality of the heart structure.ResultsA novel heterozygous missense variant, FOXC1 c.518G>A (p.R173H) was identified in the ASD family by whole exome sequencing. Subsequently, other 4 heterozygous variants in FOXC1, including 2 novel missense variants: c.556‐558delAAG (p.K186del) and c.559G>A (p.D187N) were identified in unrelated 335 sporadic ASD patients. In dual‐luciferase reporter assay, the transcriptional activity of R173H decreased to almost 30% of the wild‐type. In the Foxc1 R173H site‐specific mutant mice, the atrial septum became very thin in tissue slices of the heart that was similar to the echocardiographic finding in the above family members.ConclusionVariants in FOXC1 likely cause cardiac anomaly, particularly ASD. These findings provide a new insight into genetic mechanisms and counseling of familial and sporadic ASD.