rs757552268
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Variant summary
Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PVS1_StrongPM2PP3_ModeratePP5_Very_Strong
The NM_000387.6(SLC25A20):c.326+1del variant causes a splice donor change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000558 in 1,613,208 control chromosomes in the GnomAD database, with no homozygous occurrence. 1/1 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★★).
Frequency
Genomes: 𝑓 0.000026 ( 0 hom., cov: 31)
Exomes 𝑓: 0.000059 ( 0 hom. )
Consequence
SLC25A20
NM_000387.6 splice_donor
NM_000387.6 splice_donor
Scores
Not classified
Clinical Significance
Conservation
PhyloP100: 7.57
Genes affected
SLC25A20 (HGNC:1421): (solute carrier family 25 member 20) This gene product is one of several closely related mitochondrial-membrane carrier proteins that shuttle substrates between cytosol and the intramitochondrial matrix space. This protein mediates the transport of acylcarnitines into mitochondrial matrix for their oxidation by the mitochondrial fatty acid-oxidation pathway. Mutations in this gene are associated with carnitine-acylcarnitine translocase deficiency, which can cause a variety of pathological conditions such as hypoglycemia, cardiac arrest, hepatomegaly, hepatic dysfunction and muscle weakness, and is usually lethal in new born and infants. [provided by RefSeq, Jul 2008]
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ACMG classification
Classification made for transcript
Verdict is Pathogenic. Variant got 16 ACMG points.
PVS1
Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.1401766 fraction of the gene. Cryptic splice site detected, with MaxEntScore 7.7, offset of 0 (no position change), new splice context is: tcaGTgagt. 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;
PP3
Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
PP5
Variant 3-48883995-AC-A is Pathogenic according to our data. Variant chr3-48883995-AC-A is described in ClinVar as [Pathogenic]. Clinvar id is 345943.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
Transcripts
RefSeq
Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | MANE | UniProt |
---|---|---|---|---|---|---|---|
SLC25A20 | NM_000387.6 | c.326+1del | splice_donor_variant | ENST00000319017.5 |
Ensembl
Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | TSL | MANE | Appris | UniProt |
---|---|---|---|---|---|---|---|---|---|
SLC25A20 | ENST00000319017.5 | c.326+1del | splice_donor_variant | 1 | NM_000387.6 | P1 | |||
SLC25A20 | ENST00000430379.5 | c.198+7984del | intron_variant | 3 | |||||
SLC25A20 | ENST00000440964.1 | c.*156+1del | splice_donor_variant, NMD_transcript_variant | 2 |
Frequencies
GnomAD3 genomes AF: 0.0000263 AC: 4AN: 152116Hom.: 0 Cov.: 31
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GnomAD3 exomes AF: 0.0000360 AC: 9AN: 249670Hom.: 0 AF XY: 0.0000444 AC XY: 6AN XY: 135098
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GnomAD4 exome AF: 0.0000589 AC: 86AN: 1461092Hom.: 0 Cov.: 31 AF XY: 0.0000564 AC XY: 41AN XY: 726884
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GnomAD4 genome AF: 0.0000263 AC: 4AN: 152116Hom.: 0 Cov.: 31 AF XY: 0.0000135 AC XY: 1AN XY: 74304
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ClinVar
Significance: Pathogenic
Submissions summary: Pathogenic:6
Revision: criteria provided, multiple submitters, no conflicts
LINK: link
Submissions by phenotype
Carnitine acylcarnitine translocase deficiency Pathogenic:4
Pathogenic, criteria provided, single submitter | clinical testing | Women's Health and Genetics/Laboratory Corporation of America, LabCorp | Oct 05, 2018 | Variant summary: SLC25A20 c.326+1delG is located in a canonical splice-site and is predicted to affect mRNA splicing resulting in a significantly altered protein due to either exon skipping, shortening, or inclusion of intronic material. Five out five computational tools predict a significant impact on normal splicing consistent with multiple publications reporting experimental evidence that this variant affects mRNA splicing (Yang_2001, Hsu_2001). The variant allele was found at a frequency of 2.5e-05 in 244468 control chromosomes (gnomAD). c.326+1delG has been reported in the literature in multiple individuals affected with Carnitine-Acylcarnitine Translocase Deficiency (Yang_2001, Hsu_2001, Korman_2006), at-least one of whom was reported to have no Carnitine Acyltranslocase activity (Korman_2006). These data indicate that the variant is very likely to be associated with disease. Two ClinVar submissions from clinical diagnostic laboratories (evaluation after 2014) cites the variant as likely pathogenic/pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. - |
Pathogenic, criteria provided, single submitter | clinical testing | Illumina Laboratory Services, Illumina | Apr 27, 2017 | The SLC25A20 c.326+1delG variant occurs in a canonical splice site (donor) and is therefore predicted to disrupt or distort the normal gene product. The variant has been reported in three studies in which it is found in a total of four individuals with carnitine-acylcarnitine translocase deficiency including in a homozygous state in two siblings and in a compound heterozygous state in two unrelated individuals (Yang et al. 2001; Hsu et al. 2001; Korman et al. 2006). The c.326+1delG variant was absent from 30 healthy controls and is reported at a frequency of 0.00006 in the European (non-Finnish) population of the Exome Aggregation Consortium. Functional studies in individual fibroblasts showed a total absence of CACT enzyme activity while RT-PCR analysis revealed the variant resulted in skipping of either exon 3 or both exon 3 and exon 4 in individual RNA (Yang et al. 2001; Hsu et al. 2001; Korman et al. 2006). Based on the collective evidence and potential impact of splice site variants, the c.326+1delG variant is classified as pathogenic for carnitine-acylcarnitine translocase deficiency. This variant was observed by ICSL as part of a predisposition screen in an ostensibly healthy population. - |
Pathogenic, criteria provided, single submitter | clinical testing | Invitae | Jan 25, 2024 | This sequence change creates a premature translational stop signal (Splice site) in the SLC25A20 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in SLC25A20 are known to be pathogenic (PMID: 25614308). This variant is present in population databases (rs757552268, gnomAD 0.005%). This premature translational stop signal has been observed in individuals with carnitine-acylcarnitine translocase deficiency (PMID: 11350184, 11592821, 15365988, 16919490). This variant is also known as 388 1-G deletion and 326+1del. ClinVar contains an entry for this variant (Variation ID: 345943). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. - |
Pathogenic, criteria provided, single submitter | clinical testing | Baylor Genetics | Feb 24, 2024 | - - |
not provided Pathogenic:1
Pathogenic, criteria provided, single submitter | clinical testing | GeneDx | Jan 17, 2023 | Observed in trans with another variant in SLC25A20 in unrelated patients with SLC25A20-related carnitine-acylcarnitine translocase deficiency (Hsu et al., 2001; Korman et al., 2006); Canonical splice site variant predicted to result in a null allele in a gene for which loss of function is a known mechanism of disease; Not observed at significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 32070364, 25614308, 33634872, 31589614, 36109795, 11592821, 11350184, 16919490) - |
SLC25A20-related disorder Pathogenic:1
Pathogenic, criteria provided, single submitter | clinical testing | PreventionGenetics, part of Exact Sciences | Dec 18, 2023 | The SLC25A20 c.326+1delG variant is predicted to result in a deletion affecting a canonical splice site. This variant has been reported in the homozygous or compound heterozygous state in clinically affected individuals with enzymatically or biochemically confirmed carnitine-acylcarnitine translocase (CACT) deficiency (Yang et al 2001. PubMed ID: 11350184, described as 388g deletion; Korman SH et al 2006. PubMed ID: 16919490; Bhattacharya K et al 2020. PubMed ID: 32070364). RNA studies have shown that the c.326+1del variant leads to aberrant splicing, primarily skipping of SLC25A20 exon 3 or exons 3 and 4 together (Yang et al 2001. PubMed ID: 11350184; Korman SH et al 2006. PubMed ID: 16919490). This variant is reported in 0.0080% of alleles in individuals of European (Non-Finnish) descent in gnomAD (http://gnomad.broadinstitute.org/variant/3-48921428-AC-A). Taken together, this variant is interpreted as pathogenic. - |
Computational scores
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SpliceAI score (max)
Details are displayed if max score is > 0.2
DS_DG_spliceai
Position offset: 3
DS_DL_spliceai
Position offset: 2
Find out detailed SpliceAI scores and Pangolin per-transcript scores at