Genetic Variant SMAD4:p.Pro303Pro (chr18-51059870-T-G) – ACMG Classification: Benign (-21 pts)

Variant summary

Our verdict is Benign. The variant received -21 ACMG points: 0P and 21B. BP4_StrongBP6_Very_StrongBP7BS1BS2

The NM_005359.6(SMAD4):c.909T>G(p.Pro303Pro) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000161 in 1,612,460 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 Likely benign (★★). Synonymous variant affecting the same amino acid position (i.e. P303P) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.000053 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000012 ( 0 hom. )

Consequence

SMAD4
NM_005359.6 synonymous

Scores

Clinical Significance

Benign/Likely benign criteria provided, multiple submitters, no conflicts B:10

Conservation

PhyloP100: 1.29

Publications

4 publications found

Variant links:

COSMIC-nc: COSV61686935

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: Benign. The variant received -21 ACMG points.

BP4

Computational evidence support a benign effect (BayesDel_noAF=-0.54).

BP6

Variant 18-51059870-T-G is Benign according to our data. Variant chr18-51059870-T-G is described in ClinVar as Benign/Likely_benign. ClinVar VariationId is 460571.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

BP7

Synonymous conserved (PhyloP=1.29 with no splicing effect.

BS1

Variant frequency is greater than expected in population amr. GnomAd4 allele frequency = 0.0000526 (8/152220) while in subpopulation AMR AF = 0.000262 (4/15282). AF 95% confidence interval is 0.0000888. There are 0 homozygotes in GnomAd4. There are 6 alleles in the male GnomAd4 subpopulation. Median coverage is 32. This position passed quality control check.

BS2

High AC in GnomAd4 at 8 AD gene.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_005359.6. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein
SMAD4	NM_005359.6	MANE Select	c.909T>G	p.Pro303Pro	synonymous	Exon 8 of 12	NP_005350.1
SMAD4	NM_001407041.1		c.909T>G	p.Pro303Pro	synonymous	Exon 8 of 12	NP_001393970.1
SMAD4	NM_001407042.1		c.909T>G	p.Pro303Pro	synonymous	Exon 8 of 12	NP_001393971.1

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein
SMAD4	ENST00000342988.8	TSL:5 MANE Select	c.909T>G	p.Pro303Pro	synonymous	Exon 8 of 12	ENSP00000341551.3
SMAD4	ENST00000591126.5	TSL:1	n.2910T>G		non_coding_transcript_exon	Exon 4 of 8
SMAD4	ENST00000714264.1		c.909T>G	p.Pro303Pro	synonymous	Exon 8 of 12	ENSP00000519545.1

Frequencies

GnomAD3 genomes

AF:

0.0000526

AC:

AN:

152220

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000262

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:

0.0000441

Gnomad OTH

AF:

0.000478

GnomAD2 exomes

AF:

0.0000119

AC:

AN:

251374

AF XY:

0.00000736

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000578

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00000880

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000123

AC:

AN:

1460240

Hom.:

Cov.:

AF XY:

0.0000124

AC XY:

AN XY:

726526

show subpopulations

African (AFR)

AF:

0.0000598

AC:

AN:

33438

American (AMR)

AF:

0.0000671

AC:

AN:

44718

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26110

East Asian (EAS)

AF:

0.00

AC:

AN:

39606

South Asian (SAS)

AF:

0.00

AC:

AN:

86214

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53400

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5758

European-Non Finnish (NFE)

AF:

0.00000990

AC:

AN:

1110672

Other (OTH)

AF:

0.0000332

AC:

AN:

60324

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.456

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:

0.0000526

AC:

AN:

152220

Hom.:

Cov.:

AF XY:

0.0000807

AC XY:

AN XY:

74368

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41458

American (AMR)

AF:

0.000262

AC:

AN:

15282

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3470

East Asian (EAS)

AF:

0.00

AC:

AN:

5202

South Asian (SAS)

AF:

0.00

AC:

AN:

4836

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10624

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.0000441

AC:

AN:

68028

Other (OTH)

AF:

0.000478

AC:

AN:

2092

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.556

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:

0.00

Hom.:

Bravo

AF:

0.0000340

EpiCase

AF:

0.0000545

EpiControl

AF:

0.0000593

ClinVar

Significance: Benign/Likely benign

Submissions summary: Benign:10

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Hereditary cancer-predisposing syndrome

Benign:3

Sep 07, 2017

Color Diagnostics, LLC DBA Color Health

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Dec 08, 2020

Sema4, Sema4

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:curation

Dec 22, 2024

Molecular Diagnostics Laboratory, Catalan Institute of Oncology

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

BP4, BP7 c.909T>G located in exon 8 of the SMAD4 gene is predicted to result in no amino acid change, p.(Pro303=) (BP7).This variant is found in 3/268176 alleles at a frequency of 0.0011% in the gnomAD v2.1.1 database (non-cancer data set), and in 2/35106 alleles at a frequency of 0.006% within the Latino population. The SpliceAI algorithm predicts no significant impact on splicing (BP4). To our knowledge, neither clinical data nor functional studies have been reported for this variant. In addition, the variant was also identified in the ClinVar (2x benign, 6x likely benign) and LOVD (2x likely benign) databases. Based on currently available information, the variant c.909T>G should be considered a likely benign variant.

not provided

Benign:2

Apr 28, 2021

GeneDx

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Not observed at a significant frequency in large population cohorts (Lek et al., 2016)

Jan 25, 2018

Quest Diagnostics Nichols Institute San Juan Capistrano

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Juvenile polyposis/hereditary hemorrhagic telangiectasia syndrome

Benign:2

Mar 20, 2025

Myriad Genetics, Inc.

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This variant is considered benign. This variant is a silent/synonymous amino acid change and it is not expected to impact splicing.

Feb 05, 2024

All of Us Research Program, National Institutes of Health

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

not specified

Benign:1

Jan 15, 2021

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

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

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

Benign:1

Aug 22, 2015

Ambry Genetics

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This alteration is classified as likely 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.

Juvenile polyposis syndrome

Benign:1

Jan 26, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

BayesDel_noAF

Benign

-0.54

CADD

Benign

7.3

(source)

DANN

Benign

0.63

PhyloP100

1.3

Mutation Taster

=100/0

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

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over