chr18-51078331-G-A

Variant names:

• chr18-51078331-G-A
• rs1555687572
• NM_005359.6:c.1523G>A

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PM1 PM2 PP3_Strong PP5_Moderate

The NM_005359.6(SMAD4):​c.1523G>A​(p.Gly508Asp) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,882 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 13/22 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: SMAD4 NM_005359.6 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 9.83
• 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

ACMG classification

Our verdict: Pathogenic. The variant received 10 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 15 uncertain in NM_005359.6
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.994
• PP5: Variant 18-51078331-G-A is Pathogenic according to our data. Variant chr18-51078331-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 549766.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SMAD4	NM_005359.6	c.1523G>A	p.Gly508Asp	missense_variant	Exon 12 of 12	ENST00000342988.8	NP_005350.1
SMAD4	NM_001407041.1	c.1523G>A	p.Gly508Asp	missense_variant	Exon 12 of 12		NP_001393970.1
SMAD4	NM_001407042.1	c.1523G>A	p.Gly508Asp	missense_variant	Exon 12 of 12		NP_001393971.1
SMAD4	NR_176265.1	n.2174G>A		non_coding_transcript_exon_variant	Exon 13 of 13

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SMAD4	ENST00000342988.8	c.1523G>A	p.Gly508Asp	missense_variant	Exon 12 of 12	5	NM_005359.6	ENSP00000341551.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461882 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 727242

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44722

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86256

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53420

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1112006

Other (OTH) AF: 0.00 AC: 0 AN: 60394

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Generalized juvenile polyposis/juvenile polyposis coli Pathogenic:1

May 01, 2018

University of Washington Department of Laboratory Medicine, University of Washington

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: research

The SMAD4 variant designated as NM_005359.5:c.1523G>A (p.Gly508Asp) is as likely pathogenic. Testing in parents confirmed this variant be de novo in a patient with clinical history of juvenile polyposis syndrome beginning in their late teens and a negative family history for polyposis. This variant is highly conserved. It is not listed in population databases (ExAC or gnomAD). It is predicted to be damaging by in silico software programs (SIFT: “Damaging”, PolyPhen-2 “Probably Damaging”). The combined results are consistent with a classification of likely pathogenic. Bayesian analysis integrating all of this data (Tavtigian et al, 2018, PMID:29300386) gives 98% probability of pathogenicity, which is consistent with a classification of likely pathogenic. This variant is predicted to alter SMAD4 function and increase cancer risk. This analysis was performed in conjunction with the family studies project as part of the University of Washington Find My Variant Study. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.58	D
BayesDel_noAF	Pathogenic	0.59
CADD	Pathogenic	31
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	1.0	D;D;D
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	1.1
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	0.99	.;D;D
M_CAP	Pathogenic	0.93	D
MetaRNN	Pathogenic	0.99	D;D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	3.8	H;H;.
PhyloP100		9.8
PrimateAI	Pathogenic	0.93	D
PROVEAN	Pathogenic	-6.6	D;D;.
REVEL	Pathogenic	0.98
Sift	Uncertain	0.0010	D;D;.
Sift4G	Pathogenic	0.0	D;D;D
Polyphen		1.0	D;D;.
Vest4		0.92
MutPred		0.98		Loss of MoRF binding (P = 0.075);Loss of MoRF binding (P = 0.075);.;
MVP		1.0
MPC		3.3
ClinPred		0.99	D
GERP RS		6.1
Varity_R		0.96
gMVP		0.99
Mutation Taster		=0/100	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs1555687572; hg19: chr18-48604701; COSMIC: COSV61685672; COSMIC: COSV61685672;