chr1-226982735-C-T
Variant summary
Our verdict is Pathogenic. Variant got 15 ACMG points: 15P and 0B. PM1PM2PM5PP3PP5_Very_Strong
The NM_020247.5(COQ8A):c.911C>T(p.Ala304Val) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000403 in 1,613,568 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A304T) has been classified as Likely pathogenic.
Frequency
Consequence
NM_020247.5 missense
Scores
Clinical Significance
Conservation
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ACMG classification
Verdict is Pathogenic. Variant got 15 ACMG points.
Transcripts
RefSeq
Ensembl
Gene | Transcript | HGVSc | HGVSp | Effect | Exon rank | TSL | MANE | Protein | Appris | UniProt |
---|---|---|---|---|---|---|---|---|---|---|
COQ8A | ENST00000366777.4 | c.911C>T | p.Ala304Val | missense_variant | Exon 7 of 15 | 1 | NM_020247.5 | ENSP00000355739.3 | ||
ENSG00000288674 | ENST00000366779.6 | n.*5638C>T | non_coding_transcript_exon_variant | Exon 24 of 32 | 2 | ENSP00000355741.2 | ||||
ENSG00000288674 | ENST00000366779.6 | n.*5638C>T | 3_prime_UTR_variant | Exon 24 of 32 | 2 | ENSP00000355741.2 |
Frequencies
GnomAD3 genomes AF: 0.0000197 AC: 3AN: 152194Hom.: 0 Cov.: 33
GnomAD3 exomes AF: 0.0000399 AC: 10AN: 250734Hom.: 0 AF XY: 0.0000516 AC XY: 7AN XY: 135788
GnomAD4 exome AF: 0.0000424 AC: 62AN: 1461374Hom.: 0 Cov.: 33 AF XY: 0.0000495 AC XY: 36AN XY: 726972
GnomAD4 genome AF: 0.0000197 AC: 3AN: 152194Hom.: 0 Cov.: 33 AF XY: 0.0000135 AC XY: 1AN XY: 74346
ClinVar
Submissions by phenotype
not provided Pathogenic:4
Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 29482223, 27106809, 22036850, 33622667, 37476682, 32337771, 27142713, 35872528, 33949708, 29255295, 34638552, 33677064) -
COQ8A: PM2, PM3, PM5, PP3 -
This sequence change replaces alanine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 304 of the COQ8A protein (p.Ala304Val). This variant is present in population databases (rs748118737, gnomAD 0.008%). This missense change has been observed in individuals with clinical features of coenzyme Q10 deficiency (PMID: 22036850, 27142713, 29482223, 33949708, 37476682). ClinVar contains an entry for this variant (Variation ID: 381728). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) indicates that this missense variant is expected to disrupt COQ8A protein function with a positive predictive value of 80%. This variant disrupts the p.Ala304 amino acid residue in COQ8A. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 22036850; internal data). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. For these reasons, this variant has been classified as Pathogenic. -
The frequency of this variant in the general population is consistent with pathogenicity. (http://gnomad.broadinstitute.org) This variant has been identified homozygous in multiple unrelated individuals with clinical features associated with this gene. Polyphen and MutationTaster predict this amino acid change may be damaging to the protein. -
Autosomal recessive ataxia due to ubiquinone deficiency Pathogenic:4
The observed missense c.911C>T(p.Ala304Val) variant in COQ8A gene has been reported previously in homozygous and compound heterozygous state in individuals affected with coenzyme Q deficiency (Hughes BG, et al., 2017; Horvath R, et al., 2012). The p.Ala304Val variant has been reported with allele frequency of 0.004% in gnomAD Exomes. This variant has been reported to the ClinVar database as Uncertain Significance / Likely Pathogenic (multiple submissions). Multiple lines of computational evidences (Polyphen - Probably damaging, SIFT - Damaging and MutationTaster - Disease causing) predict a damaging effect on protein structure and function for this variant. The amino acid change p.Ala304Val in COQ8A is predicted as conserved by GERP++ and PhyloP across 100 vertebrates. The amino acid Ala at position 304 is changed to a Val changing protein sequence and it might alter its composition and physico-chemical properties. Another missense variant [c.910G>A p.Ala304Thr] on the same residue of this gene has previously been reported to be disease causing (Horvath R, et al., 2012), suggesting that this residue might be of clinical significance. However, additional functional studies will be required to prove the pathogenicity of this variant. For these reasons, this variant has been classified as Likely Pathogenic. Another significant variant [c.215A>G p.Gln72Arg] in COQ8A gene has been identified in heterozygous state in the spouse. -
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This sequence change is predicted to replace alanine with valine at codon 304 of the COQ8A protein (p.Ala304Val). The alanine residue is highly conserved (100 vertebrates, UCSC), and is located in an alpha-helix. There is a small physicochemical difference between alanine and valine, but the substitution is predicted to cause a steric clash with Pro335 and Ala338 (PMID: 25498144). The variant is present in a large population cohort at a frequency of 0.004%, which is consistent with recessive conditions (rs748118737, 11/282,096 alleles, 0 homozygotes in gnomAD v2.1). It has been identified in the homozygous state in two unrelated individuals with cerebellar ataxia (PMID: 22036850, 27142713). In one of these individuals non-genetic biochemical tests in a muscle biopsy were conducted to confirm coenzyme Q10 deficiency, and showed combined respiratory chain deficiency and significantly decreased coenzyme Q10 (PMID: 22036850). Multiple lines of computational evidence predict a deleterious effect for the missense substitution (6/7 algorithms). Additionally, another missense substitution at this position (p.Ala304Thr) has been identified in an individual with cerebellar ataxia (PMID: 22036850). Based on the classification scheme RMH ACMG Guidelines v1.1.1, this variant is classified as LIKELY PATHOGENIC. Following criteria are met: PM2, PM3, PP3, PP4. -
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Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at