The Experts below are selected from a list of 168 Experts worldwide ranked by ideXlab platform

Toshiyasu Kugimiya - One of the best experts on this subject based on the ideXlab platform.

Helen M Arthur - One of the best experts on this subject based on the ideXlab platform.

  • nonsynonymous variants in the smad6 gene predispose to congenital Cardiovascular Malformation
    Human Mutation, 2012
    Co-Authors: Elise Glen, Ana Topf, Darroch Hall, John Osullivan, Linda Sneddon, Christopher Wren, Peter Avery, Richard J Lewis, Peter Ten Dijke, Helen M Arthur
    Abstract:

    Congenital Cardiovascular Malformation (CVM) exhibits familial predisposition, but most of the specific genetic factors involved are unknown. Postulating that rare variants in genes in critical cardiac developmental pathways predispose to CVM, we systematically surveyed three genes of the bone morphogenetic protein (BMP) signaling pathway for novel variants. Exonic, splice site, and untranslated regions of BMPR1A, BMPR2, and SMAD6 genes were sequenced in 90 unrelated sporadic cases of CVM. One nonsynonymous variant (p.C484F) with predicted functional impact was found in the MAD homology 2 domain of SMAD6, an intracellular inhibitor of BMP signaling. Sequencing this domain in an additional 346 cases of CVM yielded two further nonsynonymous variants (p.P415L and p.A325T). Functional effects of all three SMAD6 mutations were investigated using BMP signaling assays in vitro. Two SMAD6 variants (p.C484F and p.P415L) had significantly (P < 0.05) lower activity than wild-type SMAD6 in inhibiting BMP signaling in a transcriptional reporter assay. In addition, the p.C484F variant had a significantly (P < 0.05) lower capacity to inhibit an osteogenic response to BMP signaling. We conclude that low-frequency deleterious variants in SMAD6 predispose to CVM. This is the first report of a human disease phenotype related to genetic variation in SMAD6. Hum Mutat 33:720–727, 2012. © 2012 Wiley Periodicals, Inc.

  • 132 non synonymous smad6 mutations impaired inhibition of bmp signalling in patients with congenital Cardiovascular Malformation
    Heart, 2011
    Co-Authors: Elise Glen, Ana Topf, Darroch Hall, John Osullivan, Linda Sneddon, Christopher Wren, Peter Avery, Richard J Lewis, Ten P Dijke, Helen M Arthur
    Abstract:

    Introduction Congenital Cardiovascular Malformation (CVM) exhibits familial predisposition but the specific genetic factors involved are unknown. Bone morphogenetic proteins (BMPs) regulate many processes during development, including cardiac development. Five genes of the BMP signalling were surveyed for novel variants predisposing to CVM risk. One of the genes, SMAD6 , functions as an inhibitory SMAD which preferentially inhibits BMP signalling. The SMAD6 knockout mouse is characterised by cardiac valve and outflow tract defects, including aortic ossification. We hypothesised that rare functional variation in SMAD6 could predispose to congenital Cardiovascular Malformation (CVM). Methods The coding regions of BMP2 , BMP4 , BMPR1A , BMPR2 and SMAD6 were sequenced in 90 unrelated Caucasian cases of CVM. The MH2 domain of SMAD6 were further sequenced in additional 346 CVM patients. Functional effects of the wild-type and variant SMAD6 proteins were expressed in C2C12 cells and their capacity to inhibit ALK3 activated expression of a BMP-responsive reporter, or to inhibit osteogenic differentiation (using an alkaline phosphatase assay) was assessed. Results We identified two novel non-synonymous variants, P415L and C484F, that were not present in 1000 ethnically-matched controls. P415L was identified in a patient with congenital aortic stenosis and C484F was identified in a patient with coarctation and calcification of the aorta. Both mutations are in evolutionarily conserved amino acid residues and are predicted to be damaging by in silico analysis. This was confirmed in functional assays as both SMAD6 variants failed to inhibit BMP signalling compared with wild-type SMAD6. The P415L mutant appeared to be hypomorphic whereas C484F appeared to be a null allele in the luciferase assay. The C484F mutant had a significantly (p Conclusions This is the first time that functional mutations in SMAD6 have been described in patients with CVM, specifically those with calcific aortic Malformations. Our data suggest that inadequate inhibition of BMP signalling pathway due to genetic variation in SMAD6 may be an important factor in CVM.

Hitoshi Hirose - One of the best experts on this subject based on the ideXlab platform.

Lippincott Williams Wilkins - One of the best experts on this subject based on the ideXlab platform.

Ana Topf - One of the best experts on this subject based on the ideXlab platform.

  • nonsynonymous variants in the smad6 gene predispose to congenital Cardiovascular Malformation
    Human Mutation, 2012
    Co-Authors: Elise Glen, Ana Topf, Darroch Hall, John Osullivan, Linda Sneddon, Christopher Wren, Peter Avery, Richard J Lewis, Peter Ten Dijke, Helen M Arthur
    Abstract:

    Congenital Cardiovascular Malformation (CVM) exhibits familial predisposition, but most of the specific genetic factors involved are unknown. Postulating that rare variants in genes in critical cardiac developmental pathways predispose to CVM, we systematically surveyed three genes of the bone morphogenetic protein (BMP) signaling pathway for novel variants. Exonic, splice site, and untranslated regions of BMPR1A, BMPR2, and SMAD6 genes were sequenced in 90 unrelated sporadic cases of CVM. One nonsynonymous variant (p.C484F) with predicted functional impact was found in the MAD homology 2 domain of SMAD6, an intracellular inhibitor of BMP signaling. Sequencing this domain in an additional 346 cases of CVM yielded two further nonsynonymous variants (p.P415L and p.A325T). Functional effects of all three SMAD6 mutations were investigated using BMP signaling assays in vitro. Two SMAD6 variants (p.C484F and p.P415L) had significantly (P < 0.05) lower activity than wild-type SMAD6 in inhibiting BMP signaling in a transcriptional reporter assay. In addition, the p.C484F variant had a significantly (P < 0.05) lower capacity to inhibit an osteogenic response to BMP signaling. We conclude that low-frequency deleterious variants in SMAD6 predispose to CVM. This is the first report of a human disease phenotype related to genetic variation in SMAD6. Hum Mutat 33:720–727, 2012. © 2012 Wiley Periodicals, Inc.

  • 132 non synonymous smad6 mutations impaired inhibition of bmp signalling in patients with congenital Cardiovascular Malformation
    Heart, 2011
    Co-Authors: Elise Glen, Ana Topf, Darroch Hall, John Osullivan, Linda Sneddon, Christopher Wren, Peter Avery, Richard J Lewis, Ten P Dijke, Helen M Arthur
    Abstract:

    Introduction Congenital Cardiovascular Malformation (CVM) exhibits familial predisposition but the specific genetic factors involved are unknown. Bone morphogenetic proteins (BMPs) regulate many processes during development, including cardiac development. Five genes of the BMP signalling were surveyed for novel variants predisposing to CVM risk. One of the genes, SMAD6 , functions as an inhibitory SMAD which preferentially inhibits BMP signalling. The SMAD6 knockout mouse is characterised by cardiac valve and outflow tract defects, including aortic ossification. We hypothesised that rare functional variation in SMAD6 could predispose to congenital Cardiovascular Malformation (CVM). Methods The coding regions of BMP2 , BMP4 , BMPR1A , BMPR2 and SMAD6 were sequenced in 90 unrelated Caucasian cases of CVM. The MH2 domain of SMAD6 were further sequenced in additional 346 CVM patients. Functional effects of the wild-type and variant SMAD6 proteins were expressed in C2C12 cells and their capacity to inhibit ALK3 activated expression of a BMP-responsive reporter, or to inhibit osteogenic differentiation (using an alkaline phosphatase assay) was assessed. Results We identified two novel non-synonymous variants, P415L and C484F, that were not present in 1000 ethnically-matched controls. P415L was identified in a patient with congenital aortic stenosis and C484F was identified in a patient with coarctation and calcification of the aorta. Both mutations are in evolutionarily conserved amino acid residues and are predicted to be damaging by in silico analysis. This was confirmed in functional assays as both SMAD6 variants failed to inhibit BMP signalling compared with wild-type SMAD6. The P415L mutant appeared to be hypomorphic whereas C484F appeared to be a null allele in the luciferase assay. The C484F mutant had a significantly (p Conclusions This is the first time that functional mutations in SMAD6 have been described in patients with CVM, specifically those with calcific aortic Malformations. Our data suggest that inadequate inhibition of BMP signalling pathway due to genetic variation in SMAD6 may be an important factor in CVM.

  • genetic variation in vegf does not contribute significantly to the risk of congenital Cardiovascular Malformation
    PLOS ONE, 2009
    Co-Authors: Helen Griffin, Ana Topf, Darroch Hall, John Osullivan, James A Eden, Graham A Stuart, Jonathan M Parsons, Ian Peart, J E Deanfield, Sonya V Babunarayan
    Abstract:

    Several previous studies have investigated the role of common promoter variants in the vascular endothelial growth factor (VEGF) gene in causing congenital Cardiovascular Malformation (CVM). However, results have been discrepant between studies and no study to date has comprehensively characterised variation throughout the gene. We genotyped 771 CVM cases, of whom 595 had the outflow tract Malformation Tetralogy of Fallot (TOF), and carried out TDT and case-control analyses using haplotype-tagging SNPs in VEGF. We carried out a meta-analysis of previous case-control or family-based studies that had typed VEGF promoter SNPs, which included an additional 570 CVM cases. To identify rare variants potentially causative of CVM, we carried out mutation screening in all VEGF exons and splice sites in 93 TOF cases. There was no significant effect of any VEGF haplotype-tagging SNP on the risk of CVM in our analyses of 771 probands. When the results of this and all previous studies were combined, there was no significant effect of the VEGF promoter SNPs rs699947 (OR 1.05 [95% CI 0.95–1.17]); rs1570360 (OR 1.17 [95% CI 0.99–1.26]); and rs2010963 (OR 1.04 [95% CI 0.93–1.16]) on the risk of CVM in 1341 cases. Mutation screening of 93 TOF cases revealed no VEGF coding sequence variants and no changes at splice consensus sequences. Genetic variation in VEGF appears to play a small role, if any, in outflow tract CVM susceptibility.