18-51078370-C-T

Variant names:

Variant summary

Our verdict is Likely pathogenic. The variant received 8 ACMG points: 8P and 0B. PM1PM2PP3_Strong

The NM_005359.6(SMAD4):c.1562C>T(p.Thr521Ile) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,862 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. T521P) has been classified as Uncertain significance.

Frequency

Genomes: not found (cov: 32)

Exomes 𝑓: 6.8e-7 ( 0 hom. )

Consequence

SMAD4
NM_005359.6 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:2

Conservation

PhyloP100: 7.78

Publications

4 publications found

Variant links:

COSMIC-nc: COSV61685222

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]

SMAD4 Gene-Disease associations (from GenCC):

juvenile polyposis/hereditary hemorrhagic telangiectasia syndrome
Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), ClinGen, Genomics England PanelApp, G2P, PanelApp Australia
Myhre syndrome
Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: ClinGen, Orphanet, G2P, Labcorp Genetics (formerly Invitae)
generalized juvenile polyposis/juvenile polyposis coli
Inheritance: AD Classification: STRONG, SUPPORTIVE Submitted by: Orphanet, Genomics England PanelApp
juvenile polyposis syndrome
Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
familial thoracic aortic aneurysm and aortic dissection
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
hereditary hemorrhagic telangiectasia
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
pulmonary arterial hypertension
Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen

SMAD4 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_pathogenic. The variant received 8 ACMG points.

PM1

In a domain MH2 (size 229) in uniprot entity SMAD4_HUMAN there are 34 pathogenic changes around while only 2 benign (94%) in NM_005359.6

PM2

Very rare variant in population databases, with high coverage;

PP3

MetaRNN computational evidence supports a deleterious effect, 0.99

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein
SMAD4	NM_005359.6 link	c.1562C>T	p.Thr521Ile	missense_variant	Exon 12 of 12	ENST00000342988.8	NP_005350.1
SMAD4	NM_001407041.1 link	c.1562C>T	p.Thr521Ile	missense_variant	Exon 12 of 12		NP_001393970.1
SMAD4	NM_001407042.1 link	c.1562C>T	p.Thr521Ile	missense_variant	Exon 12 of 12		NP_001393971.1
SMAD4	NR_176265.1 link	n.2213C>T		non_coding_transcript_exon_variant	Exon 13 of 13

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SMAD4	ENST00000342988.8 link	c.1562C>T	p.Thr521Ile	missense_variant	Exon 12 of 12	5	NM_005359.6	ENSP00000341551.3

Frequencies

GnomAD3 genomes

Cov.:

GnomAD2 exomes

AF:

0.00000398

AC:

AN:

251454

AF XY:

0.00

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00000879

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

6.84e-7

AC:

AN:

1461862

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

727224

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33480

American (AMR)

AF:

0.00

AC:

AN:

44720

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26136

East Asian (EAS)

AF:

0.00

AC:

AN:

39700

South Asian (SAS)

AF:

0.00

AC:

AN:

86258

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53420

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

8.99e-7

AC:

AN:

1111986

Other (OTH)

AF:

0.00

AC:

AN:

60394

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.575

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

Cov.:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Hereditary cancer-predisposing syndrome;C4707243:Familial thoracic aortic aneurysm and aortic dissection

Uncertain:1

Jan 13, 2025

Ambry Genetics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The p.T521I variant (also known as c.1562C>T), located in coding exon 11 of the SMAD4 gene, results from a C to T substitution at nucleotide position 1562. The threonine at codon 521 is replaced by isoleucine, an amino acid with similar properties. This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Based on the available evidence, the clinical significance of this variant remains unclear.

Juvenile polyposis syndrome

Uncertain:1

Aug 13, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change replaces threonine, which is neutral and polar, with isoleucine, which is neutral and non-polar, at codon 521 of the SMAD4 protein (p.Thr521Ile). This variant is present in population databases (no rsID available, gnomAD 0.0009%). 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: 232559). 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) has been performed at Invitae for this missense variant, however the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on SMAD4 protein function. 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: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

1.0

BayesDel_addAF

Pathogenic

0.57

BayesDel_noAF

Pathogenic

0.58

CADD

Uncertain

(source)

DANN

Uncertain

1.0

DEOGEN2

Pathogenic

1.0

D;D;D

Eigen

Pathogenic

0.87

Eigen_PC

Pathogenic

0.86

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Benign

0.0

.;D;D

M_CAP

Pathogenic

0.87

MetaRNN

Pathogenic

0.99

D;D;D

MetaSVM

Pathogenic

1.1

MutationAssessor

Pathogenic

3.9

H;H;.

PhyloP100

7.8

PrimateAI

Pathogenic

0.92

PROVEAN

Pathogenic

-5.7

D;D;.

REVEL

Pathogenic

0.90

Sift

Uncertain

0.0010

D;D;.

Sift4G

Pathogenic

0.0010

D;D;D

Vest4

0.96

ClinPred

1.0

GERP RS

6.1

Varity_R

0.80

gMVP

0.98

Mutation Taster

=46/54

disease causing

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.0

Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over