rs759918870

Positions:

• chr21-46002695-GCCCAGATCTGCATAGGTGCGCATGGGGCCACCCGGGCAGT-G

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PVS1_Moderate PM2 PP5_Moderate

The NM_001848.3(COL6A1):​c.2431_2434+36del variant causes a splice donor, splice donor 5th base, coding sequence, intron change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000131 in 152,198 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Pathogenic (★). Synonymous variant affecting the same amino acid position (i.e. A807A) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.000013 (0 hom., cov: 35)
  • Exomes 𝑓: 0.0000082 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: COL6A1 NM_001848.3 splice_donor, splice_donor_5th_base, coding_sequence, intron
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 7.37

Genes affected

COL6A1 (HGNC:2211): (collagen type VI alpha 1 chain) The collagens are a superfamily of proteins that play a role in maintaining the integrity of various tissues. Collagens are extracellular matrix proteins and have a triple-helical domain as their common structural element. Collagen VI is a major structural component of microfibrils. The basic structural unit of collagen VI is a heterotrimer of the alpha1(VI), alpha2(VI), and alpha3(VI) chains. The alpha2(VI) and alpha3(VI) chains are encoded by the COL6A2 and COL6A3 genes, respectively. The protein encoded by this gene is the alpha 1 subunit of type VI collagen (alpha1(VI) chain). Mutations in the genes that code for the collagen VI subunits result in the autosomal dominant disorder, Bethlem myopathy. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.059280854 fraction of the gene. Cryptic splice site detected, with MaxEntScore 6.2, offset of 0 (no position change), new splice context is: tagGTgcgc. Cryptic site results in inframe change. If cryptic site found is not functional and variant results in exon loss, it results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 21-46002695-GCCCAGATCTGCATAGGTGCGCATGGGGCCACCCGGGCAGT-G is Pathogenic according to our data. Variant chr21-46002695-GCCCAGATCTGCATAGGTGCGCATGGGGCCACCCGGGCAGT-G is described in ClinVar as [Pathogenic]. Clinvar id is 542987.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
COL6A1	NM_001848.3	c.2431_2434+36del		splice_donor_variant, splice_donor_5th_base_variant, coding_sequence_variant, intron_variant	33/35	ENST00000361866.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
COL6A1	ENST00000361866.8	c.2431_2434+36del		splice_donor_variant, splice_donor_5th_base_variant, coding_sequence_variant, intron_variant	33/35	1	NM_001848.3	P1

Frequencies

GnomAD3 genomes AF: 0.0000131 AC: 2 AN: 152198 Hom.: 0 Cov.: 35

Gnomad AFR AF: 0.0000483

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: 0.00

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.0000161 AC: 4 AN: 248576 Hom.: 0 AF XY: 0.0000149 AC XY: 2 AN XY: 134614

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000579

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000179

Gnomad OTH exome AF: 0.00

GnomAD4 exome Data not reliable, filtered out with message: AS_VQSR AF: 0.00000821 AC: 12 AN: 1460980 Hom.: 0 AF XY: 0.00000550 AC XY: 4 AN XY: 726784

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000224

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000989

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.0000131 AC: 2 AN: 152198 Hom.: 0 Cov.: 35 AF XY: 0.00 AC XY: 0 AN XY: 74338

Gnomad4 AFR AF: 0.0000483

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: 0.00

Gnomad4 OTH AF: 0.00

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Bethlem myopathy 1A Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Invitae

Dec 11, 2017

This sequence change removes the last 4 nucleotides of exon 33, and affects a donor splice site in intron 33 of the COL6A1 gene. It is expected to disrupt RNA splicing and likely results in an absent or disrupted protein product. The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the ExAC database. For these reasons, this variant has been classified as Pathogenic. Donor and acceptor splice site variants typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in COL6A1 are known to be pathogenic (PMID: 19884007, 20976770). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may create or strengthen a splice site, but this prediction has not been confirmed by published transcriptional studies. Experimental studies and prediction algorithms are not available for this variant, and the functional significance of the disrupted amino acids is currently unknown. This variant has not been reported in the literature in individuals with COL6A1-related disease. -

Computational scores

Source: dbNSFP v4.3

Splicing

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs759918870; hg19: chr21-47422609;