rs113360085
Variant summary
Our verdict is Likely benign. Variant got -4 ACMG points: 2P and 6B. PM2BP4BP6BS1
The NM_004369.4(COL6A3):c.3445C>T(p.Arg1149Trp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000354 in 1,614,102 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). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R1149Q) has been classified as Likely benign.
Frequency
Consequence
NM_004369.4 missense
Scores
Clinical Significance
Conservation
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ACMG classification
Verdict is Likely_benign. Variant got -4 ACMG points.
Transcripts
RefSeq
Ensembl
Frequencies
GnomAD3 genomes AF: 0.000263 AC: 40AN: 152130Hom.: 0 Cov.: 32
GnomAD3 exomes AF: 0.000187 AC: 47AN: 251266Hom.: 0 AF XY: 0.000177 AC XY: 24AN XY: 135844
GnomAD4 exome AF: 0.000364 AC: 532AN: 1461854Hom.: 0 Cov.: 32 AF XY: 0.000370 AC XY: 269AN XY: 727232
GnomAD4 genome AF: 0.000263 AC: 40AN: 152248Hom.: 0 Cov.: 32 AF XY: 0.000228 AC XY: 17AN XY: 74442
ClinVar
Submissions by phenotype
not provided Uncertain:5
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A variant of uncertain significance has been identified in the COL6A3 gene. The R1149W variant has been reported previously in an individual with a clinical diagnosis of limb-girdle muscular dystrophy who also had a second COL6A3 variant identified; however, parental studies were not reported, and this patient also had two variants identified in the NEB gene (Savarese et al., 2014). The R1149W variant is observed in 2/10,366 (0.02%) alleles from individuals of African background (Lek et al., 2016; 1000 Genomes Consortium et al., 2015; Exome Variant Server). The R1149W variant is a non-conservative amino acid substitution, which is likely to impact secondary protein structure as these residues differ in polarity, charge, size and/or other properties. However, this substitution occurs at a position that is not conserved. In silico analysis is inconsistent in its predictions as to whether or not the variant is damaging to the protein structure/function. Therefore, based on the currently available information, it is unclear whether this variant is a pathogenic variant or a rare benign variant. -
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The COL6A3 p.Arg542Trp variant was not identified in the literature but was identified in dbSNP (ID: rs113360085) and ClinVar (classified as uncertain significance by EGL Genetic Diagnostics, GeneDx, and Invitae, and as likely benign by Illumina). The variant was identified in control databases in 56 of 282644 chromosomes at a frequency of 0.0001981 (Genome Aggregation Database March 6, 2019, v2.1.1). The variant was observed in the following populations: European (non-Finnish) in 45 of 129010 chromosomes (freq: 0.000349) and Latino in 11 of 35436 chromosomes (freq: 0.00031), but was not observed in the African, Ashkenazi Jewish, East Asian, European (Finnish), Other, or South Asian populations. The p.Arg542 residue is not conserved in mammals and computational analyses (PolyPhen-2, SIFT, AlignGVGD, BLOSUM, MutationTaster) provide inconsistent predictions regarding the impact to the protein; this information is not very predictive of pathogenicity. The variant occurs outside of the splicing consensus sequence and in silico or computational prediction software programs (SpliceSiteFinder, MaxEntScan, NNSPLICE, GeneSplicer) do not predict a difference in splicing. In summary, based on the above information the clinical significance of this variant cannot be determined with certainty at this time. This variant is classified as a variant of uncertain significance. -
not specified Uncertain:1
Variant summary: COL6A3 c.3445C>T (p.Arg1149Trp) results in a non-conservative amino acid change located in the von Willebrand factor (vWF) type A domain (IPR002035) of the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 0.00019 in 251266 control chromosomes. This frequency is not significantly higher than estimated for a pathogenic variant in COL6A3 causing Ullrich congenital muscular dystrophy 1-AR (0.00019 vs 0.0035), allowing no conclusion about variant significance. c.3445C>T has been reported in the literature in at least one compound heterozygous individual affected with Limb-girdle muscular dystrophy carrying a second variant classified as benign in the presence of additional variants in the NEB gene (e.g. Savarese_2014). This report does not provide unequivocal conclusions about association of the variant with Ullrich congenital muscular dystrophy 1-AR. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publication has been ascertained in the context of this evaluation (PMID: 25214167). ClinVar contains an entry for this variant (Variation ID: 284774). Based on the evidence outlined above, the variant was classified as uncertain significance. -
Collagen 6-related myopathy Benign:1
This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). Publications were found based on this search. The evidence from the literature, in combination with allele frequency data from public databases where available, was sufficient to determine this variant is unlikely to cause disease. Therefore, this variant is classified as likely benign. -
Bethlem myopathy 1A Benign:1
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Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at