15-66703278-CGG-C

Variant names:

• chr15-66703278-CGG-C
• NM_005585.5:c.23_24delGG

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PVS1 PM2

The NM_005585.5(SMAD6):​c.23_24delGG​(p.Gly8AlafsTer36) variant causes a frameshift change. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: not found (cov: 33)
• Consequence: SMAD6 NM_005585.5 frameshift
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 4.46
• Publications: 0 publications found

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

ACMG classification

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	c.23_24delGG	p.Gly8AlafsTer36	frameshift_variant	Exon 1 of 4	ENST00000288840.10	NP_005576.3
SMAD6	NR_027654.2	n.1046_1047delGG		non_coding_transcript_exon_variant	Exon 1 of 5
SMAD6	XR_931827.3	n.1046_1047delGG		non_coding_transcript_exon_variant	Exon 1 of 4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SMAD6	ENST00000288840.10	c.23_24delGG	p.Gly8AlafsTer36	frameshift_variant	Exon 1 of 4	1	NM_005585.5	ENSP00000288840.5
SMAD6	ENST00000557916.5	n.23_24delGG		non_coding_transcript_exon_variant	Exon 1 of 5	1		ENSP00000452955.1
SMAD6	ENST00000612349.1	n.205_206delGG		non_coding_transcript_exon_variant	Exon 1 of 1	6

Frequencies

GnomAD3 genomes Cov.: 33

We have no GnomAD4 exomes data on this position. Probably position not covered by the project.

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Aortic valve disease 2 Uncertain:1

Oct 08, 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.Gly8Alafs*36) 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		4.5

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

Other links and lift over

hg19: chr15-66995616;