18-51030642-C-T

Variant names:

• chr18-51030642-C-T
• rs974217374
• NM_005359.6:c.-128+19C>T

Variant summary

Our verdict is Likely benign. Variant got -5 ACMG points: 2P and 7B. PM2 BP4_Moderate BS1_Supporting BS2

The NM_005359.6(SMAD4):​c.-128+19C>T variant causes a intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000335 in 149,410 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 Uncertain significance (★).

• Frequency:
  • Genomes: 𝑓 0.000033 (0 hom., cov: 31)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: SMAD4 NM_005359.6 intron
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.797

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]

ENSG00000267699 (HGNC:):

ACMG classification

Verdict is Likely_benign. Variant got -5 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.35).
• BS1: Variant frequency is greater than expected in population nfe. gnomad4 allele frequency = 0.0000335 (5/149410) while in subpopulation NFE AF= 0.0000598 (4/66842). AF 95% confidence interval is 0.00002. There are 0 homozygotes in gnomad4. There are 3 alleles in male gnomad4 subpopulation. Median coverage is 31. This position pass quality control queck. Existence of Clinvar submissions makes me limit the strength of this signal to Supporting
• BS2: High AC in GnomAd4 at 5 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SMAD4	NM_005359.6	c.-128+19C>T		intron_variant	Intron 1 of 11	ENST00000342988.8	NP_005350.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SMAD4	ENST00000342988.8	c.-128+19C>T		intron_variant	Intron 1 of 11	5	NM_005359.6	ENSP00000341551.3
ENSG00000267699	ENST00000590722.2	n.158-16278C>T		intron_variant	Intron 2 of 8	2		ENSP00000465737.1

Frequencies

GnomAD3 genomes AF: 0.0000335 AC: 5 AN: 149410 Hom.: 0 Cov.: 31

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.000293

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000598

Gnomad OTH AF: 0.00

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 680 Hom.: 0 Cov.: 0 AF XY: 0.00 AC XY: 0 AN XY: 362

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.0000335 AC: 5 AN: 149410 Hom.: 0 Cov.: 31 AF XY: 0.0000412 AC XY: 3 AN XY: 72804

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.000293

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000598

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000712 Hom.: 0

Bravo AF: 0.0000453

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Uncertain:1

Jan 03, 2018

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is denoted SMAD4 c.-128+19C>T or IVS1+19C>T and consists of a C>T nucleotide substitution at the +19 position of intron 1 of the SMAD4 gene. This variant is not predicted to cause abnormal splicing; however, in the absence of RNA or functional studies, the actual effect of this variant is unknown. This variant has not, to our knowledge, been published in the literature as pathogenic or benign. SMAD4 c.-128+19C>T was not observed in approximately 6,500 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project, suggesting it is not a common benign variant in these populations. The cytosine (C) nucleotide that is altered is conserved in mammals. Based on currently available information, it is unclear whether SMAD4 c.-128+19C>T is pathogenic or benign. We consider it to be a variant of uncertain significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.35
CADD	Benign	18
DANN	Uncertain	0.99

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: rs974217374; hg19: chr18-48557012;