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

Genomes: 𝑓 0.000026 ( 0 hom., cov: 32)
Exomes 𝑓: 0.000011 ( 0 hom. )

Consequence

DARS2
NM_018122.5 splice_donor, intron

Scores

4
2
1
Splicing: ADA: 1.000
2

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:6U:1

Conservation

PhyloP100: 5.10
Variant links:
Genes affected
DARS2 (HGNC:25538): (aspartyl-tRNA synthetase 2, mitochondrial) The protein encoded by this gene belongs to the class-II aminoacyl-tRNA synthetase family. It is a mitochondrial enzyme that specifically aminoacylates aspartyl-tRNA. Mutations in this gene are associated with leukoencephalopathy with brainstem and spinal cord involvement and lactate elevation (LBSL). [provided by RefSeq, Nov 2009]

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Uncertain_significance. Variant got 5 ACMG points.

PVS1
Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.05263158 fraction of the gene. Cryptic splice site detected, with MaxEntScore 5.8, offset of 4, new splice context is: gagGTagtt. Cryptic site results in frameshift change. If cryptic site found is not functional and variant results in exon loss, it results in inframe change.
PM2
Very rare variant in population databases, with high coverage;
PP5
Variant 1-173830763-T-G is Pathogenic according to our data. Variant chr1-173830763-T-G is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 449386.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=4, Uncertain_significance=1, Pathogenic=1}. Variant chr1-173830763-T-G is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene Transcript HGVSc HGVSp Effect Exon rank MANE Protein UniProt
DARS2NM_018122.5 linkc.396+2T>G splice_donor_variant, intron_variant Intron 4 of 16 ENST00000649689.2 NP_060592.2 Q6PI48Q9H9J7
DARS2NM_001365212.1 linkc.396+2T>G splice_donor_variant, intron_variant Intron 4 of 15 NP_001352141.1
DARS2NM_001365213.2 linkc.396+2T>G splice_donor_variant, intron_variant Intron 4 of 13 NP_001352142.1

Ensembl

Gene Transcript HGVSc HGVSp Effect Exon rank TSL MANE Protein Appris UniProt
DARS2ENST00000649689.2 linkc.396+2T>G splice_donor_variant, intron_variant Intron 4 of 16 NM_018122.5 ENSP00000497569.1 Q6PI48

Frequencies

GnomAD3 genomes
AF:
0.0000263
AC:
4
AN:
152194
Hom.:
0
Cov.:
32
show subpopulations
Gnomad AFR
AF:
0.00
Gnomad AMI
AF:
0.00
Gnomad AMR
AF:
0.000262
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:
0.0000278
AC:
7
AN:
251456
Hom.:
0
AF XY:
0.0000221
AC XY:
3
AN XY:
135904
show subpopulations
Gnomad AFR exome
AF:
0.00
Gnomad AMR exome
AF:
0.000145
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:
0.00
Gnomad OTH exome
AF:
0.000326
GnomAD4 exome
AF:
0.0000110
AC:
16
AN:
1459596
Hom.:
0
Cov.:
30
AF XY:
0.00000964
AC XY:
7
AN XY:
726292
show subpopulations
Gnomad4 AFR exome
AF:
0.00
Gnomad4 AMR exome
AF:
0.000246
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:
0.00000270
Gnomad4 OTH exome
AF:
0.0000332
GnomAD4 genome
AF:
0.0000263
AC:
4
AN:
152194
Hom.:
0
Cov.:
32
AF XY:
0.0000269
AC XY:
2
AN XY:
74352
show subpopulations
Gnomad4 AFR
AF:
0.00
Gnomad4 AMR
AF:
0.000262
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
Bravo
AF:
0.0000302
ExAC
AF:
0.00000824
AC:
1

ClinVar

Significance: Conflicting classifications of pathogenicity
Submissions summary: Pathogenic:6Uncertain:1
Revision: criteria provided, conflicting classifications
LINK: link

Submissions by phenotype

Leukoencephalopathy with brain stem and spinal cord involvement-high lactate syndrome Pathogenic:4
Oct 31, 2018
Fulgent Genetics, Fulgent Genetics
Significance: Pathogenic
Review Status: criteria provided, single submitter
Collection Method: clinical testing

- -

Jun 21, 2022
Laboratorio de Genetica e Diagnostico Molecular, Hospital Israelita Albert Einstein
Significance: Likely pathogenic
Review Status: criteria provided, single submitter
Collection Method: clinical testing

ACMG classification criteria: PVS1 strong, PS4 supporting, PM2 moderated, PM3 supporting -

Apr 11, 2023
Genome-Nilou Lab
Significance: Likely pathogenic
Review Status: criteria provided, single submitter
Collection Method: clinical testing

- -

Jan 16, 2025
Broad Center for Mendelian Genomics, Broad Institute of MIT and Harvard
Significance: Likely pathogenic
Review Status: criteria provided, single submitter
Collection Method: curation

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
Jan 15, 2025
GeneDx
Significance: Uncertain significance
Review Status: criteria provided, single submitter
Collection Method: clinical testing

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) -

Feb 23, 2024
Labcorp Genetics (formerly Invitae), Labcorp
Significance: Likely pathogenic
Review Status: criteria provided, single submitter
Collection Method: clinical testing

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
Aug 12, 2021
Ambry Genetics
Significance: Likely pathogenic
Review Status: criteria provided, single submitter
Collection Method: clinical testing

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: dbNSFP v4.3

Name
Calibrated prediction
Score
Prediction
BayesDel_addAF
Pathogenic
0.44
D
BayesDel_noAF
Pathogenic
0.39
CADD
Pathogenic
32
DANN
Uncertain
0.99
Eigen
Pathogenic
1.1
Eigen_PC
Pathogenic
0.94
FATHMM_MKL
Uncertain
0.95
D
GERP RS
6.1
RBP_binding_hub_radar
0.0
RBP_regulation_power_radar
1.1

Splicing

Name
Calibrated prediction
Score
Prediction
dbscSNV1_ADA
Pathogenic
1.0
dbscSNV1_RF
Pathogenic
0.94
SpliceAI score (max)
0.99
Details are displayed if max score is > 0.2
DS_DG_spliceai
0.21
Position offset: 2
DS_DL_spliceai
0.99
Position offset: -2

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

Publications

LitVar

Below is the list of publications found by LitVar. It may be empty.

Other links and lift over

dbSNP: rs759123043; hg19: chr1-173799901; API