rs281875323

chr18-51047084-A-Gchr18-51047084-A-T

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 1P and 1B. PP2 BP4

The NM_005359.6(SMAD4):c.38A>G(p.Asn13Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000411 in 1,461,540 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). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. N13D) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000041 (0 hom.)
• Consequence: SMAD4 NM_005359.6 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:7 B:1 O:2
• Conservation: PhyloP100: 7.43

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 Uncertain_significance. Variant got 0 ACMG points.

• PP2: Missense variant where missense usually causes diseases, SMAD4
• BP4: Computational evidence support a benign effect (MetaRNN=0.27581304).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SMAD4	NM_005359.6	c.38A>G	p.Asn13Ser	missense_variant	2/12	ENST00000342988.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SMAD4	ENST00000342988.8	c.38A>G	p.Asn13Ser	missense_variant	2/12	5	NM_005359.6	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.0000119 AC: 3 AN: 251334 Hom.: 1 AF XY: 0.00 AC XY: 0 AN XY: 135830

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: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000264

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000411 AC: 6 AN: 1461540 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 727098

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: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000540

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000378

ExAC AF: 0.0000247 AC: 3

EpiCase AF: 0.00

EpiControl AF: 0.0000593

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:7 Benign:1 Other:2

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not specified Uncertain:1 Other:1

not provided, no classification provided	reference population	ITMI	Sep 19, 2013	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Sep 07, 2018	Variant summary: SMAD4 c.38A>G (p.Asn13Ser) results in a conservative amino acid change in the encoded protein sequence. Three of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 4e-06 in 249274 control chromosomes (gnomAD and publication data). The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. To our knowledge, no occurrence of c.38A>G in individuals affected with Juvenile Polyposis Syndrome and no experimental evidence demonstrating its impact on protein function have been reported. This variant has been described in a patient with idiopathic pulmonary arterial hypertension (Nasim 2011). At least two publications reported experimental evidence evaluating an impact on protein function. These results showed no damaging effect for the variant on protein stability, subcellular localization, signaling activity and interactions with Smad3, Lmo4, Rassf5, and Smad9 (Nasim 2011, Wei 2014). Three clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. All laboratories classified the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as uncertain significance. -

not provided Uncertain:1 Other:1

not provided, no classification provided	literature only	UniProtKB/Swiss-Prot	-	- -
Uncertain significance, criteria provided, single submitter	clinical testing	GeneDx	Jul 21, 2023	Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant does not alter protein structure/function; Published functional studies suggest no damaging effect: did not impact SMAD-mediated signaling or interaction with Lmo4, Rassf5 and Smad9 (Nasim et al., 2011; Wei et al., 2014); Reported in an individual with idiopathic pulmonary arterial hypertension and in 1/62 healthy East Asian individuals undergoing whole genome sequencing (Nasim et al., 2011; Bodian et al., 2014); This variant is associated with the following publications: (PMID: 25502805, 26387786, 21898662, 30084161, 24728327, 31515488) -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Color Diagnostics, LLC DBA Color Health

Jul 01, 2019

- -

Generalized juvenile polyposis/juvenile polyposis coli Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Counsyl

Jun 23, 2017

- -

Pulmonary hypertension, primary, 1 Uncertain:1

Uncertain significance, no assertion criteria provided

literature only

Rare Disease Genomics Group, St George's University of London

-

- -

Juvenile polyposis/hereditary hemorrhagic telangiectasia syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Myriad Genetics, Inc.

Apr 10, 2023

This variant is classified as a variant of uncertain significance as there is insufficient evidence to determine its impact on protein function and/or cancer risk. -

Juvenile polyposis syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Nov 28, 2023

This sequence change replaces asparagine, which is neutral and polar, with serine, which is neutral and polar, at codon 13 of the SMAD4 protein (p.Asn13Ser). This variant is present in population databases (rs281875323, gnomAD 0.0009%). This missense change has been observed in individual(s) with pulmonary arterial hypertension (PMID: 21898662). ClinVar contains an entry for this variant (Variation ID: 68788). 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. Experimental studies have shown that this missense change does not substantially affect SMAD4 function (PMID: 21898662, 25502805, 31515488). 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. -

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

Likely benign, criteria provided, single submitter

clinical testing

Ambry Genetics

Aug 02, 2022

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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.072
BayesDel_addAF	Uncertain	0.076	D
BayesDel_noAF	Benign	-0.13
Cadd	Uncertain	23
Dann	Benign	0.90
DEOGEN2	Benign	0.22	T;T;T;T;T;T;T;T
Eigen	Uncertain	0.50
Eigen_PC	Uncertain	0.59
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.96	D;.;D;D;D;D;D;D
M_CAP	Uncertain	0.085	D
MetaRNN	Benign	0.28	T;T;T;T;T;T;T;T
MetaSVM	Uncertain	0.70	D
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Pathogenic	0.80	T
Sift4G	Benign	1.0	T;T;T;T;T;T;T;T
Polyphen		0.99	.;D;.;.;.;D;.;.
Vest4		0.54, 0.54, 0.53
MutPred		0.17		Gain of disorder (P = 0.0436);Gain of disorder (P = 0.0436);Gain of disorder (P = 0.0436);Gain of disorder (P = 0.0436);Gain of disorder (P = 0.0436);Gain of disorder (P = 0.0436);Gain of disorder (P = 0.0436);Gain of disorder (P = 0.0436);
MVP		0.72
MPC		1.2
ClinPred		0.47	T
GERP RS		5.9
Varity_R		0.12
gMVP		0.55

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: rs281875323; hg19: chr18-48573454;