18-51058220-G-T
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Variant summary
Our verdict is Uncertain significance. Variant got 2 ACMG points: 3P and 1B. PM2PP2BP4
The NM_005359.6(SMAD4):c.763G>T(p.Gly255Cys) variant causes a missense change. The variant allele was found at a frequency of 0.00000137 in 1,461,880 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).
Frequency
Genomes: not found (cov: 32)
Exomes 𝑓: 0.0000014 ( 0 hom. )
Consequence
SMAD4
NM_005359.6 missense
NM_005359.6 missense
Scores
8
11
Clinical Significance
Conservation
PhyloP100: 4.05
Genes affected
SMAD4 (HGNC:6770): (SMAD family member 4) This gene encodes a member of the Smad family of signal transduction proteins. Smad proteins are phosphorylated and activated by transmembrane serine-threonine receptor kinases in response to transforming growth factor (TGF)-beta signaling. The product of this gene forms homomeric complexes and heteromeric complexes with other activated Smad proteins, which then accumulate in the nucleus and regulate the transcription of target genes. This protein binds to DNA and recognizes an 8-bp palindromic sequence (GTCTAGAC) called the Smad-binding element (SBE). The protein acts as a tumor suppressor and inhibits epithelial cell proliferation. It may also have an inhibitory effect on tumors by reducing angiogenesis and increasing blood vessel hyperpermeability. The encoded protein is a crucial component of the bone morphogenetic protein signaling pathway. The Smad proteins are subject to complex regulation by post-translational modifications. Mutations or deletions in this gene have been shown to result in pancreatic cancer, juvenile polyposis syndrome, and hereditary hemorrhagic telangiectasia syndrome. [provided by RefSeq, May 2022]
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ACMG classification
Classification made for transcript
Verdict is Uncertain_significance. Variant got 2 ACMG points.
PM2
Very rare variant in population databases, with high coverage;
PP2
Missense variant in gene, where missense usually causes diseases (based on misZ statistic), SMAD4. . Gene score misZ: 4.1308 (greater than the threshold 3.09). Trascript score misZ: 4.9346 (greater than threshold 3.09). The gene has 36 curated pathogenic missense variants (we use a threshold of 10). The gene has 52 curated benign missense variants. GenCC has associacion of the gene with familial thoracic aortic aneurysm and aortic dissection, generalized juvenile polyposis/juvenile polyposis coli, hereditary hemorrhagic telangiectasia, Myhre syndrome, pulmonary arterial hypertension, juvenile polyposis/hereditary hemorrhagic telangiectasia syndrome, juvenile polyposis syndrome.
BP4
Computational evidence support a benign effect (MetaRNN=0.3082621).
Transcripts
RefSeq
Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | MANE | Protein | UniProt |
---|---|---|---|---|---|---|---|---|
SMAD4 | NM_005359.6 | c.763G>T | p.Gly255Cys | missense_variant | 6/12 | ENST00000342988.8 | NP_005350.1 |
Ensembl
Frequencies
GnomAD3 genomes Cov.: 32
GnomAD3 genomes
Cov.:
32
GnomAD4 exome AF: 0.00000137 AC: 2AN: 1461880Hom.: 0 Cov.: 33 AF XY: 0.00000275 AC XY: 2AN XY: 727242
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GnomAD4 genome Cov.: 32
GnomAD4 genome
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32
ClinVar
Significance: Uncertain significance
Submissions summary: Uncertain:7
Revision: criteria provided, multiple submitters, no conflicts
LINK: link
Submissions by phenotype
not provided Uncertain:2
Uncertain significance, criteria provided, single submitter | clinical testing | Quest Diagnostics Nichols Institute San Juan Capistrano | May 10, 2023 | This variant has not been reported in the published literature. It also has not been reported in large, multi-ethnic general populations (http://gnomad.broadinstitute.org). Analysis of this variant using bioinformatics tools for the prediction of the effect of amino acid changes on protein structure and function yielded predictions that this variant is benign. Based on the available information, we are unable to determine the clinical significance of this variant. - |
Uncertain significance, criteria provided, single submitter | clinical testing | GeneDx | Apr 15, 2022 | Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant does not alter protein structure/function; Has not been previously published as pathogenic or benign to our knowledge; This variant is associated with the following publications: (PMID: 18823382, 22992590, 15235019) - |
Hereditary cancer-predisposing syndrome Uncertain:2
Uncertain significance, criteria provided, single submitter | clinical testing | Color Diagnostics, LLC DBA Color Health | Dec 04, 2023 | This missense variant replaces glycine with cysteine at codon 255 of the SMAD4 protein. Computational prediction suggests that this variant may not impact protein structure and function (internally defined REVEL score threshold <= 0.5, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has not been reported in individuals affected with SMAD4-related disorders in the literature. This variant has not been identified in the general population by the Genome Aggregation Database (gnomAD). The available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance. - |
Uncertain significance, criteria provided, single submitter | curation | Sema4, Sema4 | Apr 30, 2021 | - - |
Hereditary cancer-predisposing syndrome;C4707243:Familial thoracic aortic aneurysm and aortic dissection Uncertain:1
Uncertain significance, criteria provided, single submitter | clinical testing | Ambry Genetics | May 12, 2023 | The p.G255C variant (also known as c.763G>T), located in coding exon 5 of the SMAD4 gene, results from a G to T substitution at nucleotide position 763. The glycine at codon 255 is replaced by cysteine, an amino acid with highly dissimilar properties. This amino acid position is not well conserved in available vertebrate species. In addition, this alteration is predicted to be tolerated by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. - |
Juvenile polyposis/hereditary hemorrhagic telangiectasia syndrome Uncertain:1
Uncertain significance, criteria provided, single submitter | clinical testing | Baylor Genetics | Jun 22, 2023 | - - |
Juvenile polyposis syndrome Uncertain:1
Uncertain significance, criteria provided, single submitter | clinical testing | Labcorp Genetics (formerly Invitae), Labcorp | Nov 06, 2023 | This sequence change replaces glycine, which is neutral and non-polar, with cysteine, which is neutral and slightly polar, at codon 255 of the SMAD4 protein (p.Gly255Cys). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with SMAD4-related conditions. ClinVar contains an entry for this variant (Variation ID: 460565). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt SMAD4 protein function with a negative predictive value of 95%. RNA analysis performed to evaluate the impact of this missense change on mRNA splicing indicates it does not significantly alter splicing (Invitae). In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. - |
Computational scores
Source:
Name
Calibrated prediction
Score
Prediction
AlphaMissense
Benign
BayesDel_addAF
Uncertain
T
BayesDel_noAF
Benign
CADD
Uncertain
DANN
Uncertain
DEOGEN2
Uncertain
T;T
Eigen
Benign
Eigen_PC
Uncertain
FATHMM_MKL
Uncertain
D
LIST_S2
Uncertain
.;D
M_CAP
Benign
D
MetaRNN
Benign
T;T
MetaSVM
Benign
T
MutationAssessor
Benign
L;L
PrimateAI
Uncertain
T
PROVEAN
Benign
N;N
REVEL
Benign
Sift
Benign
T;T
Sift4G
Uncertain
D;D
Polyphen
B;B
Vest4
MutPred
Loss of glycosylation at T259 (P = 0.0834);Loss of glycosylation at T259 (P = 0.0834);
MVP
MPC
0.56
ClinPred
T
GERP RS
RBP_binding_hub_radar
RBP_regulation_power_radar
Varity_R
gMVP
Splicing
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Prediction
SpliceAI score (max)
Details are displayed if max score is > 0.2
Find out detailed SpliceAI scores and Pangolin per-transcript scores at