NM_005359.6:c.521C>A

Variant names:

Variant summary

Our verdict is Benign. The variant received -11 ACMG points: 0P and 11B. BP4_ModerateBP6BS1BS2

The NM_005359.6(SMAD4):c.521C>A(p.Thr174Asn) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000217 in 1,613,832 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 16/22 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. T174A) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.00014 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0000096 ( 0 hom. )

Consequence

SMAD4
NM_005359.6 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:6B:4

Conservation

PhyloP100: 2.53

Publications

3 publications found

Variant links:

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:

ENSG00000267699 (HGNC:):

ENSG00000267699 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Benign. The variant received -11 ACMG points.

BP4

Computational evidence support a benign effect (MetaRNN=0.08813912).

BP6

Variant 18-51054847-C-A is Benign according to our data. Variant chr18-51054847-C-A is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 188279.

BS1

Variant frequency is greater than expected in population afr. GnomAd4 allele frequency = 0.000138 (21/152274) while in subpopulation AFR AF = 0.000481 (20/41554). AF 95% confidence interval is 0.000319. There are 0 homozygotes in GnomAd4. There are 12 alleles in the male GnomAd4 subpopulation. Median coverage is 32. This position passed quality control check.

BS2

High AC in GnomAd4 at 21 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SMAD4	NM_005359.6 link	c.521C>A	p.Thr174Asn	missense_variant	Exon 5 of 12	ENST00000342988.8	NP_005350.1	Q13485A0A024R274

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	UniProt
SMAD4	ENST00000342988.8 link	c.521C>A	p.Thr174Asn	missense_variant	Exon 5 of 12	5	NM_005359.6	ENSP00000341551.3	Q13485
ENSG00000267699	ENST00000590722.2 link	n.*697C>A		non_coding_transcript_exon_variant	Exon 8 of 9	2		ENSP00000465737.1	E7EUB6
ENSG00000267699	ENST00000590722.2 link	n.*697C>A		3_prime_UTR_variant	Exon 8 of 9	2		ENSP00000465737.1	E7EUB6

Frequencies

GnomAD3 genomes

AF:

0.000138

AC:

AN:

152156

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.000483

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.000478

GnomAD2 exomes

AF:

0.0000358

AC:

AN:

251474

AF XY:

0.0000221

show subpopulations

Gnomad AFR exome

AF:

0.000554

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:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000958

AC:

AN:

1461558

Hom.:

Cov.:

AF XY:

0.00000963

AC XY:

AN XY:

727112

show subpopulations

African (AFR)

AF:

0.000359

AC:

AN:

33466

American (AMR)

AF:

0.00

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26132

East Asian (EAS)

AF:

0.00

AC:

AN:

39696

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:

0.00

AC:

AN:

1111708

Other (OTH)

AF:

0.0000331

AC:

AN:

60386

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.482

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.000138

AC:

AN:

152274

Hom.:

Cov.:

AF XY:

0.000161

AC XY:

AN XY:

74460

show subpopulations

African (AFR)

AF:

0.000481

AC:

AN:

41554

American (AMR)

AF:

0.00

AC:

AN:

15294

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3470

East Asian (EAS)

AF:

0.00

AC:

AN:

5186

South Asian (SAS)

AF:

0.00

AC:

AN:

4820

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10604

Middle Eastern (MID)

AF:

0.00

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68024

Other (OTH)

AF:

0.000473

AC:

AN:

2116

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.501

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.0000531

Hom.:

Bravo

AF:

0.000140

ESP6500AA

AF:

0.00113

AC:

ESP6500EA

AF:

0.00

AC:

ExAC

AF:

0.0000412

AC:

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:6Benign:4

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not provided

Uncertain:2

May 23, 2025

GeneDx

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Has not been previously reported as a pathogenic or benign germline variant to our knowledge; In silico analysis suggests that this missense variant does not alter protein structure/function; This variant is associated with the following publications: (PMID: 27363283, 25178641, 15235019, 18823382, 22992590) -

Apr 14, 2020

ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The SMAD4 c.521C>A; p.Thr174Asn variant (rs138800446), to our knowledge, is not reported in the medical literature but is reported in ClinVar (Variation ID: 188279). This variant is found in the African population with an allele frequency of 0.052% (13/24966 alleles) in the Genome Aggregation Database. The threonine at codon 174 is moderately conserved, and computational analyses (SIFT, PolyPhen-2) predict that this variant is tolerated. Due to limited information, the clinical significance of the p.Thr174Asn variant is uncertain at this time. -

Hereditary cancer-predisposing syndrome

Uncertain:1Benign:1

Jan 30, 2022

Sema4, Sema4

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:curation

- -

May 31, 2023

Color Diagnostics, LLC DBA Color Health

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Juvenile polyposis/hereditary hemorrhagic telangiectasia syndrome

Uncertain:1Benign:1

Apr 10, 2023

Myriad Genetics, Inc.

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This variant is classified as a variant of uncertain significance as there is insufficient evidence to determine its impact on protein function and/or cancer risk. -

Oct 23, 2023

All of Us Research Program, National Institutes of Health

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This missense variant replaces threonine with asparagine at codon 174 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). Splice site prediction tools suggest that this variant may not impact RNA splicing. To our knowledge, functional studies have not been performed for this variant. This variant has not been reported in individuals affected with hereditary cancer in the literature. This variant has been identified in 13/282872 chromosomes 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. -

Juvenile polyposis syndrome

Uncertain:1Benign:1

Apr 24, 2018

Counsyl

Significance:Uncertain significance

Review Status:no assertion criteria provided

Collection Method:clinical testing

This submission and the accompanying classification are no longer maintained by the submitter. For more information on current observations and classification, please contact variantquestions@myriad.com. -

Jan 08, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

not specified

Uncertain:1

Aug 22, 2022

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Variant summary: SMAD4 c.521C>A (p.Thr174Asn) results in a non-conservative amino acid change located in the MAD homology 1, Dwarfin-type domain (IPR003619) of the encoded protein sequence. Three of five in-silico tools predict a benign effect of the variant on protein function. The variant allele was found at a frequency of 3.6e-05 in 251474 control chromosomes (gnomAD). The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. To our knowledge, no occurrence of c.521C>A in individuals affected with Juvenile Polyposis Syndrome and no experimental evidence demonstrating its impact on protein function have been reported. Seven clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 and classified the variant as VUS (n=6) and likely benign (n=1). Based on the evidence outlined above, the variant was classified as uncertain significance. -

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

Benign:1

Feb 16, 2023

Ambry Genetics

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This alteration is classified as benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.078

BayesDel_addAF

Benign

-0.18

BayesDel_noAF

Benign

-0.17

CADD

Benign

(source)

DANN

Benign

0.97

DEOGEN2

Uncertain

0.48

T;T;T

Eigen

Benign

-0.13

Eigen_PC

Benign

0.12

FATHMM_MKL

Uncertain

0.94

LIST_S2

Uncertain

0.86

.;D;D

M_CAP

Benign

0.019

MetaRNN

Benign

0.088

T;T;T

MetaSVM

Benign

-0.86

MutationAssessor

Benign

1.2

L;L;.

PhyloP100

2.5

PrimateAI

Uncertain

0.58

PROVEAN

Benign

0.25

N;N;.

REVEL

Benign

0.24

Sift

Benign

0.52

T;T;.

Sift4G

Benign

0.67

T;T;T

Polyphen

0.025

B;B;.

Vest4

0.37

MVP

0.64

MPC

0.52

ClinPred

0.060

GERP RS

5.9

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.7

Varity_R

0.077

gMVP

0.29

Mutation Taster

=73/27

polymorphism

(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

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over