chr18-51054786-T-C

Variant names:

• chr18-51054786-T-C
• rs864622209
• NM_005359.6:c.460T>C

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 2P and 4B. PM2 BP4_Strong

The NM_005359.6(SMAD4):​c.460T>C​(p.Ser154Pro) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 17/22 in silico tools predict a benign 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. S154A) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: SMAD4 NM_005359.6 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 1.25
• Publications: 0 publications found

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

ENSG00000267699 (HGNC:):

ACMG classification

Our verdict: Likely_benign. The variant received -2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.050251752).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SMAD4	NM_005359.6	c.460T>C	p.Ser154Pro	missense_variant	Exon 5 of 12	ENST00000342988.8	NP_005350.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SMAD4	ENST00000342988.8	c.460T>C	p.Ser154Pro	missense_variant	Exon 5 of 12	5	NM_005359.6	ENSP00000341551.3
ENSG00000267699	ENST00000590722.2	n.*636T>C		non_coding_transcript_exon_variant	Exon 8 of 9	2		ENSP00000465737.1
ENSG00000267699	ENST00000590722.2	n.*636T>C		3_prime_UTR_variant	Exon 8 of 9	2		ENSP00000465737.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 28

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Juvenile polyposis syndrome Uncertain:1

Nov 10, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces serine, which is neutral and polar, with proline, which is neutral and non-polar, at codon 154 of the SMAD4 protein (p.Ser154Pro). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with SMAD4-related conditions. 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) performed at Invitae indicates that this missense variant is not expected to disrupt SMAD4 protein function with a negative predictive value of 95%. 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	Benign	0.062
BayesDel_addAF	Benign	-0.014	T
BayesDel_noAF	Benign	-0.26
CADD	Benign	18
DANN	Benign	0.080
DEOGEN2	Benign	0.36	T;T;T
Eigen	Benign	-0.75
Eigen_PC	Benign	-0.57
FATHMM_MKL	Benign	0.44	N
LIST_S2	Benign	0.57	.;T;T
M_CAP	Benign	0.071	D
MetaRNN	Benign	0.050	T;T;T
MetaSVM	Uncertain	-0.023	T
MutationAssessor	Benign	0.82	L;L;.
PhyloP100		1.3
PrimateAI	Benign	0.35	T
PROVEAN	Benign	0.31	N;N;.
REVEL	Benign	0.21
Sift	Benign	0.98	T;T;.
Sift4G	Benign	0.70	T;T;T
Polyphen		0.0	B;B;.
Vest4		0.16
MutPred		0.31		Gain of catalytic residue at P153 (P = 0.0216);Gain of catalytic residue at P153 (P = 0.0216);Gain of catalytic residue at P153 (P = 0.0216);
MVP		0.36
MPC		0.58
ClinPred		0.018	T
GERP RS		3.4
Varity_R		0.031
gMVP		0.30
Mutation Taster		=67/33	polymorphism

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

Other links and lift over

dbSNP: rs864622209; hg19: chr18-48581156;