rs121918206

Variant names:

• chr1-173838206-C-T
• rs121918206
• NM_018122.5:c.787C>T

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_018122.5(DARS2):​c.787C>T​(p.Arg263*) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000123 in 1,461,054 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 Pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.000012 (0 hom.)
• Consequence: DARS2 NM_018122.5 stop_gained
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:5 O:1
• Conservation: PhyloP100: 2.92

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]

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 1-173838206-C-T is Pathogenic according to our data. Variant chr1-173838206-C-T is described in ClinVar as [Pathogenic]. Clinvar id is 1059.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr1-173838206-C-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
DARS2	NM_018122.5	c.787C>T	p.Arg263*	stop_gained	Exon 9 of 17	ENST00000649689.2	NP_060592.2
DARS2	NM_001365212.1	c.787C>T	p.Arg263*	stop_gained	Exon 9 of 16		NP_001352141.1
DARS2	NM_001365213.2	c.787C>T	p.Arg263*	stop_gained	Exon 9 of 14		NP_001352142.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
DARS2	ENST00000649689.2	c.787C>T	p.Arg263*	stop_gained	Exon 9 of 17		NM_018122.5	ENSP00000497569.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.0000123 AC: 18 AN: 1461054 Hom.: 0 Cov.: 29 AF XY: 0.0000124 AC XY: 9 AN XY: 726882

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

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: 0.0000153

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 32

Bravo AF: 0.0000113

TwinsUK AF: 0.000270 AC: 1

ALSPAC AF: 0.00 AC: 0

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:5 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Leukoencephalopathy with brain stem and spinal cord involvement-high lactate syndrome Pathogenic:3 Other:1

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GenomeConnect - Brain Gene Registry

Significance: not provided

Review Status: no classification provided

Collection Method: phenotyping only

Variant classified as Pathogenic and reported on 12-27-2019 by Prevention Genetics. Assertions are reported exactly as they appear on the patient provided laboratory report. GenomeConnect does not attempt to reinterpret the variant. The IDDRC-CTSA National Brain Gene Registry (BGR) is a study funded by the U.S. National Center for Advancing Translational Sciences (NCATS) and includes 13 Intellectual and Developmental Disability Research Center (IDDRC) institutions. The study is led by Principal Investigator Dr. Philip Payne from Washington University. The BGR is a data commons of gene variants paired with subject clinical information. This database helps scientists learn more about genetic changes and their impact on the brain and behavior. Participation in the Brain Gene Registry requires participation in GenomeConnect. More information about the Brain Gene Registry can be found on the study website - https://braingeneregistry.wustl.edu/. -

Apr 01, 2007

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

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Apr 11, 2023

Genome-Nilou Lab

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Jan 21, 2025

Broad Center for Mendelian Genomics, Broad Institute of MIT and Harvard

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: curation

The p.Arg263Ter variant in DARS2 has been reported in two siblings with leukoencephalopathy with brain stem and spinal cord involvement-high lactate syndrome (PMID: 17384640, 24566671), and has been identified in 0.001% (17/1179296) of European (non-Finnish) chromosomes by the Genome Aggregation Database (gnomAD, http://gnomad.broadinstitute.org; dbSNP rs121918206). Although this variant has been seen in the general population in a heterozygous state, its frequency is low enough to be consistent with a recessive carrier frequency. This variant has also been reported in ClinVar (Variation ID: 1059) and has been interpreted as pathogenic by OMIM, Invitae, GeneDx, and Genome-Nilou Lab. In vitro functional studies provide some evidence that the p.Arg263Ter variant may impact protein function (PMID: 24566671). However, these types of assays may not accurately represent biological function. This nonsense variant leads to a premature termination codon at position 263, which is predicted to lead to a truncated or absent protein. 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, PM2_supporting, PS3_moderate (Richards 2015). -

not provided Pathogenic:2

Apr 11, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

For these reasons, this variant has been classified as Pathogenic. ClinVar contains an entry for this variant (Variation ID: 1059). This premature translational stop signal has been observed in individual(s) with leukoencephalopathy (PMID: 17384640). This variant is not present in population databases (gnomAD no frequency). This sequence change creates a premature translational stop signal (p.Arg263*) in the DARS2 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in DARS2 are known to be pathogenic (PMID: 17384640, 24566671). -

Feb 13, 2023

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Nonsense variant predicted to result in protein truncation or nonsense mediated decay in a gene for which loss-of-function is a known mechanism of disease; Not observed in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 25525159, 17384640, 26620921, 24566671) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.62
CADD	Pathogenic	38
DANN	Uncertain	1.0
Eigen	Pathogenic	0.71
Eigen_PC	Uncertain	0.58
FATHMM_MKL	Uncertain	0.95	D
Vest4		0.92
GERP RS		4.8

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		Details are displayed if max score is > 0.2

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

Publications

LitVar

Other links and lift over

dbSNP: rs121918206; hg19: chr1-173807344;