X-linked BCOR variants identified in Chinese Han patients with congenital heart disease.

BACKGROUND: Congenital heart disease (CHD) frequently manifests as a complex phenotype and approximately one-third of cases may be caused by genetic factors. BCOR, an X-linked gene encoding the corepressor of BCL6, has been demonstrated to be closely involved in human heart development. However, whether BCOR variants represent the genetic etiology underlying CHD needs further investigation. METHODS: We performed whole exome sequencing on CHD nuclear families and identified a candidate gene, BCOR, by robust bioinformatic analysis and medical literature searches. Targeted DNA sequencing of the candidate gene was conducted and then the association between variants and the risk of developing CHD was analyzed. The effects of BCOR mutations on gene expression, localization, protein interaction, and signaling pathways were evaluated in vitro. RESULTS: We identified a BCOR hemizygous missense variant (c.1448C>T, p.Pro483Leu) in a male proband presented with CHD/heterotaxy. Sanger sequencing confirmed that this variant was inherited from his asymptomatic mother. Interestingly, through literature searches, we observed another novel BCOR hemizygous missense variant (c.1619G>A, p.Arg540Gln) in a CHD patient with heterotaxy, supporting the pathogenic evidence of BCOR variants. Functional experiments conducted in vitro revealed that the variant p.Pro483Leu altered the subcellular localization of BCOR protein, disrupted its interaction with BCL6, and significantly promoted cell proliferation, whereas the variant p.Arg540Gln displayed no obvious effects. Nevertheless, transcriptional analysis revealed that down-regulation of BCOR substantially enhanced the activities of mitogen-activated protein and phosphoinositide 3-kinase-AKT signaling pathways, which are closely attributed to heart development. Targeted sequencing of 932 sporadic CHD patients enriched nine variants of BCOR predicted as likely rare and damaging and a septal defect was present in 81.8% (9/11) of them, including the two probands, which was consistent with the possible phenotype caused by BCOR defects. CONCLUSIONS: The findings of the present study indicate that variants in BCOR may predispose individuals to CHD in the Chinese Han population.

Functional analysis of HECA variants identified in congenital heart disease in the Chinese population.

BACKGROUND: Congenital heart disease (CHD) is a class of cardiovascular defects that includes septal defects, outflow tract abnormalities, and valve defects. Human homolog of Drosophila headcase (HECA) is a novel cell cycle regulator whose role in CHD has not been elucidated. This is the first study to determine the frequency of HECA mutations in patients with CHD and the association between HECA variants and CHD. METHODS: In this study, we identified a candidate gene, HECA, by whole-exome sequencing of an atrial septal defect family. To investigate the association between HECA variants and CHD risk, targeted exon sequencing was conducted in 689 individuals with sporadic CHD. We further analyzed the effect of HECA gene abnormalities on cardiomyocyte phenotype behavior and related signaling pathways by Western blotting, reverse transcription-quantitative polymerase chain reaction, and scratch assay. RESULTS: We found a novel de novo mutation, c.409_410insA (p. W137fs), in the HECA gene and identified five rare deleterious variants that met the filtering criteria in 689 individuals with sporadic CHD. Fisher's exact test revealed a significant association between HECA variations and CHD compared with those in gnomADv2-East Asians(p = 0.0027). Further functional analysis suggested that the variant p. W137fs resulted in a deficiency of the normal HECA protein, and HECA deficiency altered AC16 cell cycle progression, increased cell proliferation, and migration, and promoted the activation of the PDGF-BB/PDGFRB/AKT pathway. CONCLUSIONS: Our study identified HECA and its six rare variants, expanding the spectrum of genes associated with CHD pathogenesis in the Chinese population.

PTPN11 Gene Mutations and Its Association with the Risk of Congenital Heart Disease.

Congenital heart disease (CHD) is the most common congenital birth defect, with a prevalence of 8.98‰ of all live births in China. PTPN11 has been known to be closely involved in heart developments. In this research, we carried out whole-exome sequencing in nine CHD families and identified eight rare deleterious missense variants of PTPN11 gene in nine probands by stringently filtering criteria. Sanger sequencing of these probands and their unaffected familiar members revealed that six damaging variants were de novo in seven CHD families. Then, targeted sequencing was used to assess the PTPN11 exon variants in 672 sporadic CHD cases and 399 unrelated controls and identified 7 deleterious missense variants in 8 patients. Fisher's exact test reveals a significant association of PTPN11 variations with CHD (P = 0.0289). We observed the distribution of different subtypes in CHD patients with PTPN11 variants and found atrial septal defect (ASD) is a prominent phenotype (58.8%, 10/17). In vitro functional assays revealed that the predicted PTPN11 variants disturb RAS-mitogen-activated protein kinase signaling activity by influencing the phosphorylation level of pathway proteins and increasing the proliferation and migration abilities of cardiomyocytes to different extents. Our findings demonstrated that PTPN11 variants were associated with increased risk of CHD development and may be served as an important susceptible genetic event for CHD, especially the ASD subphenotype.