Xing-Yuan Liu

A novel GATA6 mutation in patients with tetralogy of Fallot or atrial septal defect.

GATA6 is a member of the GATA family of transcription factors, and its expression and functions overlap with those of GATA4 during heart development. Mutations in GATA4 have been related to human congenital heart diseases (CHDs) in several studies, whereas mutations in GATA6 have only recently been reported in patients with persistent truncus arteriosus. Animal experiments have revealed critical roles for GATA6 in the development of the myocardium and cardiac morphogenesis, thereby highlighting the potential involvement of GATA6 defects in the pathogenesis of CHDs. Here, we screened the GATA6 in 270 individuals with sporadic CHDs by direct sequencing. After identification of the mutation, a luciferase reporter assay and real-time quantitative polymerase chain reaction were performed to detect functional changes in the mutant transcription factor. The same heterozygous missense mutation (Ser184Asn) was identified in three patients, including one with tetralogy of Fallot and two with atrial septal defects. This mutation was not found in 500 unrelated ethnically matched healthy subjects. Direct sequencing of this region in the parents of these three patients revealed the same mutation in one of the parents for each patient, and one of the parent carriers presented with a bicuspid aortic valve. Biological analysis revealed clearly decreased transcriptional activity of GATA6 Ser184Asn in vitro. All these data suggest that GATA6 Ser184Asn is a novel mutation associated with CHDs and has an important role in disease pathogenesis.

GATA5 Loss-of-Function Mutation Responsible for the Congenital Ventriculoseptal Defect

The ventriculoseptal defect (VSD) is the most common form of congenital heart disease and a leading noninfectious cause of infant mortality. Growing evidence demonstrates that genetic defects are associated with congenital VSD. Nevertheless, VSD is genetically heterogeneous, and the molecular basis for VSD in an overwhelming majority of patients remains unknown. In this study, the whole coding region of GATA5, a gene encoding a zinc finger transcription factor crucial for normal cardiogenesis, was sequenced in 120 unrelated patients with VSD. The available relatives of the patient harboring the identified mutation and 200 unrelated individuals used as controls were subsequently genotyped. The causative potential of a sequence variation was evaluated by MutationTaster, and the functional effect of the mutation was characterized using a luciferase reporter assay system. As a result, a novel heterozygous GATA5 mutation, p.L199V, was identified in a patient with VSD, which was absent in 400 control chromosomes. Genetic analysis of the mutation carrier’s available family members showed that the substitution co-segregated with VSD transmitted in an autosomal dominant pattern. The p.L199V variation was automatically predicted to be disease causing, and the functional analysis showed that the GATA5 p.L199V mutant protein was associated with significantly reduced transcriptional activation compared with its wild-type counterpart. To the best of the authors’ knowledge, this is the first report on the link of functionally compromised GATA5 to human VSD, suggesting potential implications for the early prophylaxis and personalized treatment of VSD.

A Novel NKX2.5 Loss-of-Function Mutation Associated With Congenital Bicuspid Aortic Valve

Bicuspid aortic valve (BAV) is the most common form of congenital cardiovascular defect in humans and is associated with substantial morbidity and mortality. Emerging evidence demonstrates that genetic risk factors play an important role in the pathogenesis of BAV. However, BAV is a genetically heterogenous disorder, and the genetic defects underpinning BAV in most patients remain to be identified. In the present study, the coding exons and flanking introns of the NKX2.5 gene, which encodes a homeodomain-containing transcription factor essential for the normal development of the aortic valve, were sequenced in 142 unrelated patients with BAV. The available relatives of the mutation carrier and 200 unrelated healthy subjects used as controls were also genotyped for NKX2.5. The functional characteristics of the mutation were delineated by using a dual-luciferase reporter assay system. As a result, a novel heterozygous NKX2.5 mutation, p.K192X, was identified in a family with BAV transmitted in an autosomal dominant pattern. The nonsense mutation was absent in 400 control chromosomes. Functional analyses revealed that the mutant NKX2.5 had no transcriptional activity compared with its wild-type counterpart. Furthermore, the mutation abolished the synergistic transcriptional activation between NKX2.5 and GATA5, another transcription factor crucial for the aortic valvular morphogenesis. In conclusion, this study is the first to link an NKX2.5 loss-of-function mutation to enhanced susceptibility to human BAV, providing novel insight into the molecular mechanism of BAV and suggesting potential implications for genetic counseling and clinical care of families presenting with BAV.

GATA5 loss-of-Function Mutations Underlie Tetralogy of Fallot

Tetraology of Fallot (TOF) is the most common form of cyanotic congenital heart disease and is a major cause of significant morbidity and mortality. Emerging evidence demonstrates that genetic risk factors are involved in the pathogenesis of TOF. However, TOF is genetically heterogeneous and the genetic defects responsible for TOF remain largely unclear. In the present study, the whole coding region of the GATA5 gene, which encodes a zinc-finger transcription factor essential for cardiogenesis, was sequenced in 130 unrelated patients with TOF. The relatives of the index patients harboring the identified mutations and 200 unrelated control individuals were subsequently genotyped. The functional characteristics of the mutations were analyzed using a luciferase reporter assay system. As a result, 2 novel heterozygous GATA5 mutations, p.R187G and p.H207R, were identified in 2 families with autosomal dominantly inherited TOF, respectively. The variations were absent in 400 control alleles and the altered amino acids were completely conserved evolutionarily. Functional analysis showed that the GATA5 mutants were associated with significantly decreased transcriptional activation compared with their wild-type counterpart. To our knowledge, this is the first report on the association of GATA5 loss-of-function mutations with TOF, suggesting potential implications for the early prophylaxis and allele-specific therapy of human TOF.

A novel GATA6 mutation associated with congenital ventricular septal defect

Ventricular septal defect (VSD) is the most common form of congenital cardiovascular malformation and an important contributor to the substantially increased morbidity and mortality in infants. Emerging evidence indicates the genetic basis for the pathogenesis of congenital VSD in a significant proportion of patients. However, congenital VSD is a genetically heterogeneous disease and the genetic defects responsible for VSD in the overwhelming majority of cases remain unclear. In this study, the entire coding region of the GATA6 gene, which encodes a zinc-finger transcription factor crucial to normal cardiogenesis, was sequenced in 130 unrelated patients with congenital VSD. The available relatives of the index patient carrying the identified mutation and 200 unrelated ethnically matched healthy individuals used as controls were subsequently genotyped. The functional characteristics of the mutant GATA6 were assessed in contrast to its wild-type counterpart using a luciferase reporter assay system. As a result, a novel heterozygous missense GATA6 mutation, p.G220S, was identified in a proband with VSD. The variation was absent in 400 control chromosomes and the altered amino acid was highly conserved evolutionarily across species. Genetic analysis of the family members of the mutation carrier showed that the substitution co-segregated with VSD was inherited as an autosomal dominant trait. Functional analysis demonstrated that the p.G220S mutation of GATA6 was associated with significantly decreased transcriptional activity. The findings provide novel insight into the molecular mechanism involved in VSD, implying the potential clinical implications in the gene-specific prophylaxis and therapy of this common developmental abnormality in neonates.

A Novel GATA4 Loss-of-Function Mutation Associated With Congenital Ventricular Septal Defect

Ventricular septal defect (VSD) is the most prevalent type of congenital heart disease and a major cause for the significantly increased morbidity and mortality among infants. Aggregating evidence indicates that genetic defects are involved in the pathogenesis of congenital VSD. Nevertheless, VSD is genetically heterogeneous, and the genetic determinants for VSD in the majority of patients remain to be identified. In this study, the entire coding region of GATA4, a gene encoding a zinc finger transcription factor essential for normal cardiac morphogenesis, was sequenced in 160 unrelated patients with VSD. The available relatives of the index patient harboring the identified mutation and 200 unrelated control individuals were subsequently genotyped. The disease-causing potential of a sequence alteration was evaluated by MutationTaster, and the functional effect of the mutation was characterized using a luciferase reporter assay system. As a result, a novel heterozygous GATA4 variation, p.R43W, was identified in a proband with VSD, that was absent in control subjects. Genetic analysis of the family members of the variation carrier showed that the substitution co-segregated with VSD. The p.R43W variant was predicted to be a pathogenic mutation, and the functional analysis demonstrated that the GATA4 R43W mutant protein resulted in significantly decreased transcriptional activity compared with its wild-type counterpart. The findings expand the mutational spectrum of GATA4 linked to VSD and provide more insight into the molecular mechanism of VSD.

Prevalence and spectrum of GATA5 mutations associated with congenital heart disease

Congenital heart disease (CHD) is the most common form of birth defect and is the leading noninfectious cause of infant death. A growing body of evidence demonstrates that genetic risk factors are involved in the pathogenesis of CHD. However, CHD is a genetically heterogeneous disease and the genetic defects underlying CHD in an overwhelming majority of patients remain unclear. In this study, the whole coding region and splice junction sites of the PITX2c gene, which encodes variant 3 of paired-like homeodomain transcription factor 2 crucial for normal cardiovascular morphogenesis, were sequenced in 382 unrelated patients with CHD, and 2 novel heterozygous mutations, p.W147X and p.N153D, were identified in 2 unrelated patients with CHD, respectively, including a 1-year-old male patient with double outlet right ventricle in combination with ventricular septal defect and a 4-year-old female patient with ventricular septal defect. The mutations were absent in 400 control chromosomes and were both predicted t...

A novel GATA4 mutation responsible for congenital ventricular septal defects

Ventricular septal defect (VSD) is the most common type of cardiovascular developmental anomaly and is an important risk factor for the substantially increased morbidity and mortality in newborns. Aggregating evidence implicates genetic defects in the pathogenesis of congenital VSD. However, VSD is genetically heterogeneous and the genetic determinants for VSD in most patients remain to be identified. In this study, the whole coding region of the GATA4 gene, which encodes a zinc-finger transcription factor pivotal to cardiogenesis, was initially sequenced in 210 unrelated patients with VSD. The relatives of the index patient carrying the identified mutation and 200 unrelated ethnically-matched healthy individuals used as controls were subsequently genotyped. The functional effect of the mutant GATA4 was characterized in contrast to its wild-type counterpart using a luciferase reporter assay system. A novel heterozygous GATA4 mutation, p.G296R, was identified in a family with VSD inherited as an autosomal dominant trait. Absent in 200 control individuals, the mutation co-segregated with VSD in the family with 100% penetrance and was completely conserved evolutionarily across species. Functional analysis displayed that the p.G296R mutation of GATA4 was associated with a decreased transcriptional activity. The findings expand the spectrum of mutations in GATA4 linked to VSD and provide more insight into the molecular mechanism involved in VSD. The results of the present study imply the potential implications in the genetic diagnosis and gene-specific therapy of this common malformation in infancy.

A novel NKX2-5 mutation in familial ventricular septal defect.

Ventricular septal defect (VSD) is the most common cardiovascular malformation and an important contributor to the substantial morbidity and mortality in infancy. Growing evidence suggests that genetic defects play important roles in the pathogenesis of congenital VSD. However, VSD is of great genetic heterogeneity and the genetic basis for VSD in the majority of the patients remains largely unhnown. In this study, the entire coding region of the NKX2-5 gene, which encodes a homeodomain-containing transcription factor crucial to cardiogenesis, was initially sequenced in 136 unrelated patients with VSD. The relatives of a proband harboring the identified mutation and 200 unrelated control individuals were genotyped. The functional characteristic of the mutant transcription factor was analyzed in contrast to its wild-type counterpart using a luciferase reporter assay system. A novel heterozygous NKX2-5 mutation, p.P59A, was identified in a family with autosomal dominant inherited VSD. Absent in the 200 control individuals, the mutation was highly conserved evolutionarily and co-segregated with VSD in the family with complete penetrance. Functional analysis revealed that the p.P59A mutation of NKX2-5 was associated with a decreased transcriptional activity. These findings expand the spectrum of the mutations in NKX2-5 linked to VSD and provide new insight into the molecular mechanisms involved in VSD. The resuls of the present study may have potential implications in the genetic diagnosis and gene-specific therapy of this common childhood disease.

TBX20 loss-of-function mutation contributes to double outlet right ventricle

Congenital heart disease (CHD), the most prevalent birth defect in humans worldwide, is still a leading non‑infectious cause of infant morbidity and mortality. Increasing evidence demonstrates that genetic risk factors play a key role in the pathogenesis of CHD, and more than 50 genes have been linked to various types of CHD. Nevertheless, CHD is a heterogeneous disorder and the genetic components underpinning CHD in an overwhelming majority of cases remain unknown. In the present study, the entire coding exons and flanking introns of the TBX20 gene, which codes for a T-box transcription factor essential for the proper development of the heart, were sequenced in a cohort of 146 unrelated patients with CHD. The available relatives of the index patient harboring an identified mutation and 200 unrelated ethnically matched healthy individuals used as the controls were also genotyped for TBX20. The functional characteristics of the TBX20 mutation were assayed by using a dual-luciferase reporter assay system. As a result, a novel heterozygous TBX20 mutation, p.R143W, was identified in an index patient with double outlet right ventricle (DORV). Genetic analyses of the pedigree of the proband revealed that in the family, the mutation co-segregated with DORV transmitted in an autosomal dominant pattern with complete penetrance. The missense mutation was absent in 400 control chromosomes and the altered amino acid was completely conserved evolutionarily across species. Functional analysis revealed that mutant TBX20 had a significantly diminished transcriptional activity compared with its wild-type counterpart. To the best of our knowledge, this study is the first to report the association of TBX20 loss-of-function mutation with increased susceptibility to DORV in humans, which provides novel insight into the molecular mechanisms responsible for CHD, suggesting potential implications for the antenatal prophylaxis of CHD.