18-51058128-A-T

Variant names:

• chr18-51058128-A-T
• rs587780793
• NM_005359.6:c.671A>T

Variant summary

Our verdict is Likely benign. The variant received -3 ACMG points: 2P and 5B. PM2 BS1_Supporting BS2

The NM_005359.6(SMAD4):​c.671A>T​(p.Gln224Leu) variant causes a missense change. The variant allele was found at a frequency of 0.00000342 in 1,461,806 control chromosomes in the GnomAD database, with no homozygous occurrence. 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. Q224R) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000034 (0 hom.)
• Consequence: SMAD4 NM_005359.6 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:10 B:2
• Conservation: PhyloP100: 5.13
• Publications: 2 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 -3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BS1: Variant frequency is greater than expected in population amr. GnomAdExome4 allele frequency = 0.00000342 (5/1461806) while in subpopulation AMR AF = 0.0000671 (3/44724). AF 95% confidence interval is 0.0000178. There are 0 homozygotes in GnomAdExome4. There are 1 alleles in the male GnomAdExome4 subpopulation. Median coverage is 32. This position passed quality control check. Existence of Clinvar submissions makes me limit the strength of this signal to Supporting
• BS2: High AC in GnomAdExome4 at 5 AD gene.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_005359.6. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SMAD4	NM_005359.6	MANE Select	c.671A>T	p.Gln224Leu	missense	Exon 6 of 12	NP_005350.1
	SMAD4	NM_001407041.1		c.671A>T	p.Gln224Leu	missense	Exon 6 of 12	NP_001393970.1
	SMAD4	NM_001407042.1		c.671A>T	p.Gln224Leu	missense	Exon 6 of 12	NP_001393971.1

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SMAD4	ENST00000342988.8	TSL:5 MANE Select	c.671A>T	p.Gln224Leu	missense	Exon 6 of 12	ENSP00000341551.3
	ENSG00000267699	ENST00000590722.2	TSL:2	n.*847A>T		non_coding_transcript_exon	Exon 9 of 9	ENSP00000465737.1
	SMAD4	ENST00000591126.5	TSL:1	n.2672A>T		non_coding_transcript_exon	Exon 2 of 8

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.0000119 AC: 3 AN: 251320 AF XY: 0.00000736

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000867

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000342 AC: 5 AN: 1461806 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 727208

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

American (AMR) AF: 0.0000671 AC: 3 AN: 44724

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

East Asian (EAS) AF: 0.00 AC: 0 AN: 39694

South Asian (SAS) AF: 0.00 AC: 0 AN: 86252

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53414

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

European-Non Finnish (NFE) AF: 0.00000180 AC: 2 AN: 1111942

Other (OTH) AF: 0.00 AC: 0 AN: 60396

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000378

ClinVar

ClinVar submissions as Germline

Significance: Conflicting classifications of pathogenicity

Revision: criteria provided, conflicting classifications

Pathogenic	VUS	Benign	Condition
-	3	-	Juvenile polyposis/hereditary hemorrhagic telangiectasia syndrome (3)
-	1	1	Juvenile polyposis syndrome (2)
-	2	-	not provided (2)
-	1	-	Carcinoma of pancreas;C0345893:Juvenile polyposis syndrome;C0796081:Myhre syndrome;C1832942:Juvenile polyposis/hereditary hemorrhagic telangiectasia syndrome (1)
-	1	-	Hereditary cancer-predisposing syndrome (1)
-	-	1	Hereditary cancer-predisposing syndrome;C4707243:Familial thoracic aortic aneurysm and aortic dissection (1)
-	1	-	not specified (1)
-	1	-	SMAD4-related disorder (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.11
BayesDel_addAF	Uncertain	0.089	D
BayesDel_noAF	Uncertain	0.090
CADD	Uncertain	23
DANN	Benign	0.97
DEOGEN2	Uncertain	0.60	D
Eigen	Benign	-0.019
Eigen_PC	Benign	0.19
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.86	D
M_CAP	Benign	0.068	D
MetaRNN	Uncertain	0.53	D
MetaSVM	Benign	-0.73	T
MutationAssessor	Benign	1.4	L
PhyloP100		5.1
PrimateAI	Uncertain	0.51	T
PROVEAN	Benign	-1.4	N
REVEL	Uncertain	0.32
Sift	Benign	0.64	T
Sift4G	Benign	0.36	T
Polyphen		0.039	B
Vest4		0.68
MutPred		0.26		Gain of glycosylation at S223 (P = 0.0746)
MVP		0.94
MPC		0.45
ClinPred		0.28	T
GERP RS		5.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.12
gMVP		0.54
Mutation Taster		=85/15	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: rs587780793; hg19: chr18-48584498;