rs1555687572

Positions:

• chr18-51078331-G-A
• chr18-51078331-G-C

Variant summary

Our verdict is Pathogenic. Variant got 11 ACMG points: 11P and 0B. PM1 PM2 PP2 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. 12/21 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

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 Pathogenic. Variant got 11 ACMG points.

• PM1: In a domain MH2 (size 229) in uniprot entity SMAD4_HUMAN there are 40 pathogenic changes around while only 2 benign (95%) in NM_005359.6
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), SMAD4. . Gene score misZ 4.1308 (greater than the threshold 3.09). Trascript score misZ 4.9346 (greater than threshold 3.09). GenCC has associacion of gene with 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, 0.994
• 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/exons	MANE	Protein	UniProt
SMAD4	NM_005359.6	c.1523G>A	p.Gly508Asp	missense_variant	12/12	ENST00000342988.8	NP_005350.1
SMAD4	NM_001407041.1	c.1523G>A	p.Gly508Asp	missense_variant	12/12		NP_001393970.1
SMAD4	NM_001407042.1	c.1523G>A	p.Gly508Asp	missense_variant	12/12		NP_001393971.1
SMAD4	NR_176265.1	n.2174G>A		non_coding_transcript_exon_variant	13/13

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
SMAD4	ENST00000342988.8	c.1523G>A	p.Gly508Asp	missense_variant	12/12	5	NM_005359.6	ENSP00000341551	P1

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

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: 8.99e-7

Gnomad4 OTH exome AF: 0.00

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

Likely pathogenic, criteria provided, single submitter

research

University of Washington Department of Laboratory Medicine, University of Washington

May 01, 2018

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;.
MutationTaster	Benign	1.0	D;D;D
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

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

Publications

LitVar

Other links and lift over

dbSNP: rs1555687572; hg19: chr18-48604701; COSMIC: COSV61685672; COSMIC: COSV61685672;