1-173830763-T-G
Variant summary
Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PVS1_ModeratePM2PP5
The NM_018122.5(DARS2):c.396+2T>G variant causes a splice donor, intron change. The variant allele was found at a frequency of 0.0000124 in 1,611,790 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).
Frequency
Consequence
NM_018122.5 splice_donor, intron
Scores
Clinical Significance
Conservation
Genome browser will be placed here
ACMG classification
Verdict is Uncertain_significance. Variant got 5 ACMG points.
Transcripts
RefSeq
Gene | Transcript | HGVSc | HGVSp | Effect | Exon rank | MANE | Protein | UniProt |
---|---|---|---|---|---|---|---|---|
DARS2 | NM_018122.5 | c.396+2T>G | splice_donor_variant, intron_variant | Intron 4 of 16 | ENST00000649689.2 | NP_060592.2 | ||
DARS2 | NM_001365212.1 | c.396+2T>G | splice_donor_variant, intron_variant | Intron 4 of 15 | NP_001352141.1 | |||
DARS2 | NM_001365213.2 | c.396+2T>G | splice_donor_variant, intron_variant | Intron 4 of 13 | NP_001352142.1 |
Ensembl
Frequencies
GnomAD3 genomes AF: 0.0000263 AC: 4AN: 152194Hom.: 0 Cov.: 32
GnomAD3 exomes AF: 0.0000278 AC: 7AN: 251456Hom.: 0 AF XY: 0.0000221 AC XY: 3AN XY: 135904
GnomAD4 exome AF: 0.0000110 AC: 16AN: 1459596Hom.: 0 Cov.: 30 AF XY: 0.00000964 AC XY: 7AN XY: 726292
GnomAD4 genome AF: 0.0000263 AC: 4AN: 152194Hom.: 0 Cov.: 32 AF XY: 0.0000269 AC XY: 2AN XY: 74352
ClinVar
Submissions by phenotype
Leukoencephalopathy with brain stem and spinal cord involvement-high lactate syndrome Pathogenic:4
- -
ACMG classification criteria: PVS1 strong, PS4 supporting, PM2 moderated, PM3 supporting -
- -
The c.396+2T>G variant in DARS2 has been reported, in the compound heterozygous state, in one individual with leukoencephalopathy with brain stem and spinal cord involvement-high lactate syndrome (PMID: 17384640), but has been identified in 0.03% (15/59980) of Admixed chromosomes by the Genome Aggregation Database (gnomAD, http://gnomad.broadinstitute.org; dbSNP rs759123043). Although this variant has been seen in the general population in a heterozygous state, its frequency is not high enough to rule out a pathogenic role. This variant has also been reported in ClinVar (Variation ID: 449386) and has been interpreted as pathogenic or likely pathogenic by multiple submitters. This variant is located in the 5' splice region. Computational tools predict both an in-frame and out-of-frame cryptic splice site, providing evidence that this variant may escape NMD or lead to a truncated or absent protein. However, this information is not predictive enough to determine pathogenicity. Loss of function of the DARS2 gene is an established disease mechanism in autosomal recessive leukoencephalopathy with brain stem and spinal cord involvement-high lactate syndrome. In summary, although additional studies are required to fully establish its clinical significance, this variant is likely pathogenic for autosomal recessive leukoencephalopathy with brain stem and spinal cord involvement-high lactate syndrome. ACMG/AMP Criteria applied: PVS1_strong, PM3 (Richards 2015). -
not provided Pathogenic:1Uncertain:1
Canonical splice site variant predicted to result in an in-frame loss of the adjacent exon in a gene for which loss of function is a known mechanism of disease; This variant is associated with the following publications: (PMID: 25525159, 31589614, 17384640) -
This sequence change affects a donor splice site in intron 4 of the DARS2 gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in DARS2 are known to be pathogenic (PMID: 17384640, 24566671). This variant is present in population databases (rs759123043, gnomAD 0.02%). Disruption of this splice site has been observed in individual(s) with leukoencephalopathy with brain stem and spinal cord involvement and lactate elevation (PMID: 17384640). This variant is also known as 396+2T>G. ClinVar contains an entry for this variant (Variation ID: 449386). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -
Inborn genetic diseases Pathogenic:1
The c.396+2T>G intronic variant results from a T to G substitution two nucleotides after coding exon 4 of the DARS2 gene. Alterations that disrupt the canonical splice site are expected to result in aberrant splicing. The resulting transcript is predicted to be in-frame and is not expected to trigger nonsense-mediated mRNA decay; however, direct evidence is unavailable. The exact functional effect of the altered amino acid sequence is unknown; however, a significant portion of the protein is affected (Ambry internal data). Based on data from gnomAD, the G allele has an overall frequency of <0.01% (9/282862) total alleles studied. The c.396+2T>G alteration has been identified in the compound heterozygous state with a second DARS2 alteration (c.228-15C>A) in one individual with leukoencephalopathy with brain stem and spinal cord involvement with lactate elevation (LBSL) (Scheper, 2007). This nucleotide position is well conserved in available vertebrate species. In silico splice site analysis predicts that this alteration will weaken the native splice donor site. Based on the available evidence, this alteration is classified as likely pathogenic. -
Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at