18-51058119-C-T

Variant names:

• chr18-51058119-C-T
• rs748992694
• NM_005359.6:c.668-6C>T

Variant summary

Our verdict is Benign. The variant received -18 ACMG points: 0P and 18B. BP4_Moderate BP6_Very_Strong BS1 BS2

The NM_005359.6(SMAD4):​c.668-6C>T variant causes a splice region, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000821 in 1,461,790 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Likely benign (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000082 (0 hom.)
• Consequence: SMAD4 NM_005359.6 splice_region, intron
• Scores: Splicing: ADA: 0.0005588
• Clinical Significance: Likely benign criteria provided, multiple submitters, no conflicts B:3
• Conservation: PhyloP100: 1.24
• 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

ENSG00000267699 (HGNC:):

ACMG classification

Our verdict: Benign. The variant received -18 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.36).
• BP6: Variant 18-51058119-C-T is Benign according to our data. Variant chr18-51058119-C-T is described in ClinVar as [Likely_benign]. Clinvar id is 918783.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• BS1: Variant frequency is greater than expected in population sas. GnomAdExome4 allele frequency = 0.00000821 (12/1461790) while in subpopulation SAS AF = 0.000116 (10/86248). AF 95% confidence interval is 0.0000625. There are 0 homozygotes in GnomAdExome4. There are 4 alleles in the male GnomAdExome4 subpopulation. Median coverage is 32. This position passed quality control check.
• BS2: High AC in GnomAdExome4 at 12 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SMAD4	NM_005359.6	c.668-6C>T		splice_region_variant, intron_variant	Intron 5 of 11	ENST00000342988.8	NP_005350.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SMAD4	ENST00000342988.8	c.668-6C>T		splice_region_variant, intron_variant	Intron 5 of 11	5	NM_005359.6	ENSP00000341551.3
ENSG00000267699	ENST00000590722.2	n.*844-6C>T		splice_region_variant, intron_variant	Intron 8 of 8	2		ENSP00000465737.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.0000119 AC: 3 AN: 251270 AF XY: 0.00000736

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 FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000880

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000821 AC: 12 AN: 1461790 Hom.: 0 Cov.: 32 AF XY: 0.00000550 AC XY: 4 AN XY: 727200

African (AFR) AF: 0.00 AC: 0 AN: 33476

American (AMR) AF: 0.00 AC: 0 AN: 44724

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

East Asian (EAS) AF: 0.00 AC: 0 AN: 39692

South Asian (SAS) AF: 0.000116 AC: 10 AN: 86248

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: 8.99e-7 AC: 1 AN: 1111936

Other (OTH) AF: 0.0000166 AC: 1 AN: 60396

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

EpiCase AF: 0.00

EpiControl AF: 0.0000593

ClinVar

Significance: Likely benign

Submissions summary: Benign:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hereditary cancer-predisposing syndrome Benign:1

Jun 26, 2019

Color Diagnostics, LLC DBA Color Health

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Juvenile polyposis/hereditary hemorrhagic telangiectasia syndrome Benign:1

Mar 19, 2025

Myriad Genetics, Inc.

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is considered likely benign. This variant is intronic and is not expected to impact mRNA splicing. -

Juvenile polyposis syndrome Benign:1

Jun 07, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.36
CADD	Benign	16
DANN	Benign	0.77
PhyloP100		1.2
Mutation Taster		=88/12	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.00056
dbscSNV1_RF	Benign	0.050
SpliceAI score (max)		0.030		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: rs748992694; hg19: chr18-48584489;