rs1248541873

chr18-51048761-C-T

Variant summary

Our verdict is Likely benign. Variant got -2 ACMG points: 2P and 4B. PM2 BP4_Moderate BP6 BP7

The NM_005359.6(SMAD4):c.325C>T(p.Leu109=) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000659 in 151,730 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 Conflicting classifications of pathogenicity (no stars). Synonymous variant affecting the same amino acid position (i.e. L109L) has been classified as Likely benign.

• Frequency: Genomes: 𝑓 0.0000066 (0 hom., cov: 33)
• Consequence: SMAD4 NM_005359.6 synonymous
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:1 B:4
• Conservation: PhyloP100: 1.76

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]

ACMG classification

Verdict is Likely_benign. Variant got -2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.33).
• BP6: Variant 18-51048761-C-T is Benign according to our data. Variant chr18-51048761-C-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 492478.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=4, Uncertain_significance=1}.
• BP7: Synonymous conserved (PhyloP=1.76 with no splicing effect.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SMAD4	NM_005359.6	c.325C>T	p.Leu109=	synonymous_variant	3/12	ENST00000342988.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SMAD4	ENST00000342988.8	c.325C>T	p.Leu109=	synonymous_variant	3/12	5	NM_005359.6	P1

Frequencies

GnomAD3 genomes AF: 0.00000659 AC: 1 AN: 151730 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

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: 0.0000147

Gnomad OTH AF: 0.00

GnomAD4 exome Cov.: 32

GnomAD4 genome AF: 0.00000659 AC: 1 AN: 151730 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 74132

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000147

Gnomad4 OTH AF: 0.00

Bravo AF: 0.00000378

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:1 Benign:4

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Uncertain:1 Benign:1

Likely benign, criteria provided, single submitter	clinical testing	ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories	Mar 29, 2023	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Quest Diagnostics Nichols Institute San Juan Capistrano	Nov 03, 2022	To the best of our knowledge, the variant has not been reported in the published literature. The frequency of this variant in the general population, 0.0000066 (1/151730 chromosomes, http://gnomad.broadinstitute.org), is uninformative in assessment of its pathogenicity. Analysis of this variant using software algorithms for the prediction of the effect of nucleotide changes on splicing yielded predictions that this variant does not affect SMAD4 mRNA splicing . Based on the available information, we are unable to determine the clinical significance of this variant. -

Hereditary cancer-predisposing syndrome;C4707243:Familial thoracic aortic aneurysm and aortic dissection Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Ambry Genetics

Jun 08, 2021

This alteration is classified as likely benign based on a combination of the following: 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. -

Hereditary cancer-predisposing syndrome Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Color Diagnostics, LLC DBA Color Health

Dec 20, 2016

- -

Juvenile polyposis syndrome Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Invitae

Dec 16, 2023

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.33
Cadd	Benign	9.5
Dann	Benign	0.75

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

LitVar

Other links and lift over

dbSNP: rs1248541873; hg19: chr18-48575131; COSMIC: COSV100748367; COSMIC: COSV100748367;