Genetic Variant NM_005585.5:c.25delC (chr15-66703282-GC-G) – ACMG Classification: Pathogenic (10 pts)

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PVS1PM2

The NM_005585.5(SMAD6):c.25delC(p.Leu9TrpfsTer55) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000747 in 1,338,290 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★). Synonymous variant affecting the same amino acid position (i.e. L9L) has been classified as Likely benign.

Frequency

Genomes: not found (cov: 33)

Exomes 𝑓: 7.5e-7 ( 0 hom. )

Consequence

SMAD6
NM_005585.5 frameshift

Scores

Not classified

Clinical Significance

Uncertain significance criteria provided, single submitter U:1

Conservation

PhyloP100: 3.02

Publications

0 publications found

Variant links:

Genes affected

SMAD6 (HGNC:6772): (SMAD family member 6) The protein encoded by this gene belongs to the SMAD family of proteins, which are related to Drosophila 'mothers against decapentaplegic' (Mad) and C. elegans Sma. SMAD proteins are signal transducers and transcriptional modulators that mediate multiple signaling pathways. This protein functions in the negative regulation of BMP and TGF-beta/activin-signalling. Multiple transcript variants have been found for this gene.[provided by RefSeq, Sep 2014]

SMAD6 Gene-Disease associations (from GenCC):

craniosynostosis 7
Inheritance: AD, Unknown Classification: STRONG, MODERATE, LIMITED Submitted by: G2P, Labcorp Genetics (formerly Invitae), Ambry Genetics, PanelApp Australia
radioulnar synostosis, nonsyndromic, susceptibility to
Inheritance: AD Classification: STRONG Submitted by: Ambry Genetics
aortic valve disease 2
Inheritance: AD, Unknown Classification: MODERATE, LIMITED Submitted by: Ambry Genetics, PanelApp Australia, Labcorp Genetics (formerly Invitae)
familial bicuspid aortic valve
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
congenital radioulnar synostosis
Inheritance: AR, Unknown Classification: SUPPORTIVE, LIMITED Submitted by: Ambry Genetics, Orphanet
congenital heart defects, multiple types
Inheritance: AD Classification: LIMITED Submitted by: Ambry Genetics

SMAD6 links:

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ACMG classification

Classification was made for transcript

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

PVS1

Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant located near the start codon (<100nt), not predicted to undergo nonsense mediated mRNA decay. There are 101 pathogenic variants in the truncated region.

PM2

Very rare variant in population databases, with high coverage;

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SMAD6	NM_005585.5 link	c.25delC	p.Leu9TrpfsTer55	frameshift_variant	Exon 1 of 4	ENST00000288840.10	NP_005576.3	O43541-1
SMAD6	NR_027654.2 link	n.1048delC		non_coding_transcript_exon_variant	Exon 1 of 5
SMAD6	XR_931827.3 link	n.1048delC		non_coding_transcript_exon_variant	Exon 1 of 4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	UniProt
SMAD6	ENST00000288840.10 link	c.25delC	p.Leu9TrpfsTer55	frameshift_variant	Exon 1 of 4	1	NM_005585.5	ENSP00000288840.5	O43541-1
SMAD6	ENST00000557916.5 link	n.25delC		non_coding_transcript_exon_variant	Exon 1 of 5	1		ENSP00000452955.1	O43541-4
SMAD6	ENST00000612349.1 link	n.207delC		non_coding_transcript_exon_variant	Exon 1 of 1	6

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

7.47e-7

AC:

AN:

1338290

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

661000

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

26996

American (AMR)

AF:

0.00

AC:

AN:

27318

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

23378

East Asian (EAS)

AF:

0.00

AC:

AN:

29088

South Asian (SAS)

AF:

0.0000136

AC:

AN:

73330

European-Finnish (FIN)

AF:

0.00

AC:

AN:

47424

Middle Eastern (MID)

AF:

0.00

AC:

AN:

4258

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1051754

Other (OTH)

AF:

0.00

AC:

AN:

54744

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.575

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

Cov.:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

LINK: link

Submissions by phenotype

Aortic valve disease 2

Uncertain:1

Sep 03, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change creates a premature translational stop signal (p.Leu9Trpfs*55) in the SMAD6 gene. It is expected to result in an absent or disrupted protein product. However, the current clinical and genetic evidence is not sufficient to establish whether loss-of-function variants in SMAD6 cause disease. This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with SMAD6-related conditions. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

PhyloP100

3.0

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over