18-51048830-C-T

Position:

• chr18-51048830-C-T

Variant summary

Our verdict is Likely pathogenic. Variant got 9 ACMG points: 9P and 0B. PM1 PM2 PP2 PP3_Strong

The NM_005359.6(SMAD4):​c.394C>T​(p.His132Tyr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 12/21 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency: Genomes: not found (cov: 33)
• Consequence: SMAD4 NM_005359.6 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 7.90

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]

ENSG00000267699 (HGNC:):

ACMG classification

Verdict is Likely_pathogenic. Variant got 9 ACMG points.

• PM1: In a binding_site (size 0) in uniprot entity SMAD4_HUMAN
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in the SMAD4 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 36 curated pathogenic missense variants (we use a threshold of 10). The gene has 52 curated benign missense variants. Gene score misZ: 4.1308 (above the threshold of 3.09). Trascript score misZ: 4.9346 (above the threshold of 3.09). GenCC associations: The gene is linked to familial thoracic aortic aneurysm and aortic dissection, generalized juvenile polyposis/juvenile polyposis coli, hereditary hemorrhagic telangiectasia, Myhre syndrome, pulmonary arterial hypertension, juvenile polyposis/hereditary hemorrhagic telangiectasia syndrome, juvenile polyposis syndrome.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.974

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
SMAD4	NM_005359.6	c.394C>T	p.His132Tyr	missense_variant	3/12	ENST00000342988.8	NP_005350.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
SMAD4	ENST00000342988.8	c.394C>T	p.His132Tyr	missense_variant	3/12	5	NM_005359.6	ENSP00000341551.3
ENSG00000267699	ENST00000590722.2	n.*417C>T		non_coding_transcript_exon_variant	4/9	2		ENSP00000465737.1
ENSG00000267699	ENST00000590722.2	n.*417C>T		3_prime_UTR_variant	4/9	2		ENSP00000465737.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

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

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Aug 01, 2016

The p.H132Y variant (also known as c.394C>T), located in coding exon 2 of the SMAD4 gene, results from a C to T substitution at nucleotide position 394. The histidine at codon 132 is replaced by tyrosine, an amino acid with similar properties. This alteration has been observed in at least one individual with a personal and/or family history that is consistent with SMAD4-related disease (Ambry internal data). Based on internal structural analysis, H132Y disrupts a conserved zinc-binding site which is important to structural stability and DNA-binding (Ambry internal data; Chai J et al. J Biol Chem, 2003 May;278:20327-31; BabuRajendran N et al. Nucleic Acids Res, 2010 Jun;38:3477-88; Martin-Malpartida P et al. Nat Commun, 2017 12;8:2070). This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Juvenile polyposis syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

May 07, 2024

This sequence change replaces histidine, which is basic and polar, with tyrosine, which is neutral and polar, at codon 132 of the SMAD4 protein (p.His132Tyr). 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. ClinVar contains an entry for this variant (Variation ID: 405501). 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) has been performed at Invitae for this missense variant, however the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on SMAD4 protein function. 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	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.52	D
BayesDel_noAF	Pathogenic	0.51
CADD	Pathogenic	30
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.97	D;D;D;D;D
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.92
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	0.99	.;D;D;D;D
M_CAP	Pathogenic	0.81	D
MetaRNN	Pathogenic	0.97	D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.6	H;.;.;H;.
PrimateAI	Pathogenic	0.93	D
PROVEAN	Pathogenic	-5.5	D;.;.;D;.
REVEL	Pathogenic	0.96
Sift	Uncertain	0.0010	D;.;.;D;.
Sift4G	Pathogenic	0.0	D;D;D;D;D
Polyphen		1.0	D;.;.;D;.
Vest4		0.95
MutPred		0.84		Gain of phosphorylation at H132 (P = 0.3449);Gain of phosphorylation at H132 (P = 0.3449);Gain of phosphorylation at H132 (P = 0.3449);Gain of phosphorylation at H132 (P = 0.3449);Gain of phosphorylation at H132 (P = 0.3449);
MVP		0.99
MPC		3.0
ClinPred		0.99	D
GERP RS		5.5
Varity_R		0.98
gMVP		0.98

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: rs1060500743; hg19: chr18-48575200; COSMIC: COSV61683986; COSMIC: COSV61683986;