NM_005359.6:c.954T>C

Variant names:

• chr18-51059915-T-C
• rs773615487
• NM_005359.6:c.954T>C

Variant summary

Our verdict is Benign. Variant got -10 ACMG points: 2P and 12B. PM2 BP4_Moderate BP6 BP7 BS1 BS2

The NM_005359.6(SMAD4):​c.954T>C​(p.Pro318Pro) variant causes a splice region, synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000343 in 1,457,298 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000034 (0 hom.)
• Consequence: SMAD4 NM_005359.6 splice_region, synonymous
• Scores: Splicing: ADA: 0.0005314
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:1 B:5
• Conservation: PhyloP100: 2.38

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 Benign. Variant got -10 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.45).
• BP6: Variant 18-51059915-T-C is Benign according to our data. Variant chr18-51059915-T-C is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 387518.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=4, Uncertain_significance=1}.
• BP7: Synonymous conserved (PhyloP=2.38 with no splicing effect.
• BS1: Variant frequency is greater than expected in population sas. gnomad4_exome allele frequency = 0.00000343 (5/1457298) while in subpopulation SAS AF= 0.0000464 (4/86154). AF 95% confidence interval is 0.0000158. There are 0 homozygotes in gnomad4_exome. There are 3 alleles in male gnomad4_exome subpopulation. Median coverage is 29. This position pass quality control queck.
• BS2: High AC in GnomAdExome4 at 5 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SMAD4	NM_005359.6	c.954T>C	p.Pro318Pro	splice_region_variant, synonymous_variant	Exon 8 of 12	ENST00000342988.8	NP_005350.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SMAD4	ENST00000342988.8	c.954T>C	p.Pro318Pro	splice_region_variant, synonymous_variant	Exon 8 of 12	5	NM_005359.6	ENSP00000341551.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251352 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135844

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 SAS exome AF: 0.0000327

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000343 AC: 5 AN: 1457298 Hom.: 0 Cov.: 29 AF XY: 0.00000414 AC XY: 3 AN XY: 725352

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000464

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 9.03e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

Alfa AF: 0.0000936 Hom.: 0

Bravo AF: 0.00000756

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:1 Benign:5

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Uncertain:1

Jun 30, 2016

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is denoted SMAD4 c.954T>C at the DNA level. This variant is silent at the coding level, preserving a Proline at codon 318. It is not predicted to cause abnormal splicing. This variant has not, to our knowledge, been published in the literature as being pathogenic or benign. SMAD4 c.954T>C was not observed in approximately 6,500 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project, indicating it is not a common benign variant in these populations. The nucleotide which is altered, a thymine (T) at base 954, is conserved in mammals. Based on currently available information, it is unclear whether SMAD4 c.954T>C is a pathogenic or benign variant. We consider it to be a variant of uncertain significance. -

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

Sep 29, 2018

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. -

Hereditary cancer-predisposing syndrome Benign:1

Jan 02, 2021

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 Benign:1

Aug 15, 2023

All of Us Research Program, National Institutes of Health

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Juvenile polyposis syndrome;C0796081:Myhre syndrome;C1832942:Juvenile polyposis/hereditary hemorrhagic telangiectasia syndrome;C2931038:Familial pancreatic carcinoma Benign:1

Sep 12, 2024

Department of Pathology and Laboratory Medicine, Sinai Health System

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Juvenile polyposis syndrome Benign:1

Oct 29, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.45
CADD	Benign	15
DANN	Benign	0.87
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		2.8

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.00053
dbscSNV1_RF	Benign	0.024
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: rs773615487; hg19: chr18-48586285;