rs375657891

chr2-237348609-G-A

Variant summary

Our verdict is Likely benign. Variant got -3 ACMG points: 2P and 5B. PM2 BP4_Strong BP6

The NM_004369.4(COL6A3):c.6930+4C>T variant causes a splice donor region, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000136 in 1,613,576 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 Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: 𝑓 0.000059 (0 hom., cov: 33)
  • Exomes 𝑓: 0.00014 (0 hom.)
• Consequence: COL6A3 NM_004369.4 splice_donor_region, intron
• Scores: Splicing: ADA: 0.0004557
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:3 B:2
• Conservation: PhyloP100: -5.03

Genes affected

COL6A3 (HGNC:2213): (collagen type VI alpha 3 chain) This gene encodes the alpha-3 chain, one of the three alpha chains of type VI collagen, a beaded filament collagen found in most connective tissues. The alpha-3 chain of type VI collagen is much larger than the alpha-1 and -2 chains. This difference in size is largely due to an increase in the number of subdomains, similar to von Willebrand Factor type A domains, that are found in the amino terminal globular domain of all the alpha chains. These domains have been shown to bind extracellular matrix proteins, an interaction that explains the importance of this collagen in organizing matrix components. Mutations in the type VI collagen genes are associated with Bethlem myopathy, a rare autosomal dominant proximal myopathy with early childhood onset. Mutations in this gene are also a cause of Ullrich congenital muscular dystrophy, also referred to as Ullrich scleroatonic muscular dystrophy, an autosomal recessive congenital myopathy that is more severe than Bethlem myopathy. Multiple transcript variants have been identified, but the full-length nature of only some of these variants has been described. [provided by RefSeq, Jun 2009]

ACMG classification

Verdict is Likely_benign. Variant got -3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.78).
• BP6: Variant 2-237348609-G-A is Benign according to our data. Variant chr2-237348609-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 283047.We mark this variant Likely_benign, oryginal submissions are: {Uncertain_significance=3, Likely_benign=2}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
COL6A3	NM_004369.4	c.6930+4C>T		splice_donor_region_variant, intron_variant		ENST00000295550.9
COL6A3	NM_057166.5	c.5109+4C>T		splice_donor_region_variant, intron_variant
COL6A3	NM_057167.4	c.6312+4C>T		splice_donor_region_variant, intron_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
COL6A3	ENST00000295550.9	c.6930+4C>T		splice_donor_region_variant, intron_variant		1	NM_004369.4	P1
COL6A3	ENST00000472056.5	c.5109+4C>T		splice_donor_region_variant, intron_variant		1
COL6A3	ENST00000353578.9	c.6312+4C>T		splice_donor_region_variant, intron_variant		5
COL6A3	ENST00000491769.1	n.1184+4C>T		splice_donor_region_variant, intron_variant, non_coding_transcript_variant		5

Frequencies

GnomAD3 genomes AF: 0.0000591 AC: 9 AN: 152204 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.0000482

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.000103

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.0000995 AC: 25 AN: 251162 Hom.: 0 AF XY: 0.0000737 AC XY: 10 AN XY: 135720

Gnomad AFR exome AF: 0.0000616

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.000139

Gnomad NFE exome AF: 0.000185

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.000144 AC: 210 AN: 1461372 Hom.: 0 Cov.: 32 AF XY: 0.000125 AC XY: 91 AN XY: 727006

Gnomad4 AFR exome AF: 0.0000299

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000252

Gnomad4 SAS exome AF: 0.0000116

Gnomad4 FIN exome AF: 0.000131

Gnomad4 NFE exome AF: 0.000174

Gnomad4 OTH exome AF: 0.000116

GnomAD4 genome AF: 0.0000591 AC: 9 AN: 152204 Hom.: 0 Cov.: 33 AF XY: 0.0000672 AC XY: 5 AN XY: 74350

Gnomad4 AFR AF: 0.0000482

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.000103

Gnomad4 OTH AF: 0.00

Alfa AF: 0.000147 Hom.: 0

Bravo AF: 0.0000756

EpiCase AF: 0.000109

EpiControl AF: 0.0000593

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:3 Benign:2

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Uncertain:2 Benign:1

Uncertain significance, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Feb 19, 2020	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Sep 01, 2015	- -
Likely benign, criteria provided, single submitter	clinical testing	GeneDx	May 21, 2021	This variant is associated with the following publications: (PMID: 30564623) -

Bethlem myopathy 1A Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Dec 30, 2023

This sequence change falls in intron 29 of the COL6A3 gene. It does not directly change the encoded amino acid sequence of the COL6A3 protein. It affects a nucleotide within the consensus splice site. This variant is present in population databases (rs375657891, gnomAD 0.02%). This variant has been observed in individual(s) with clinical suspicion of limb-girdle muscular dystrophy (PMID: 30564623). ClinVar contains an entry for this variant (Variation ID: 283047). Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant is not likely to affect RNA splicing. 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. -

Collagen 6-related myopathy Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 13, 2018

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score and internal cut-off values, a variant classified as likely benign is not then subjected to further curation. The score for this variant resulted in a classification of likely benign for this disease. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.78
Cadd	Benign	0.0020
Dann	Benign	0.80

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.00046
dbscSNV1_RF	Benign	0.0020
SpliceAI score (max)		0.020		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: rs375657891; hg19: chr2-238257252;