1-173825319-C-A

Variant names:

• chr1-173825319-C-A
• rs959382650
• NM_018122.5:c.90C>A

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PVS1 PM2 PP5_Moderate

The NM_018122.5(DARS2):​c.90C>A​(p.Tyr30*) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000205 in 1,461,630 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 (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: DARS2 NM_018122.5 stop_gained
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 1.02
• Publications: 0 publications found

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]

DARS2 Gene-Disease associations (from GenCC):

• leukoencephalopathy with brain stem and spinal cord involvement-high lactate syndrome

  Inheritance: AR, AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Genomics England PanelApp, Ambry Genetics, Labcorp Genetics (formerly Invitae), G2P, Orphanet
• mitochondrial disease

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen

ACMG classification

Our verdict: Pathogenic. The variant received 12 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant located near the start codon (<100nt), not predicted to undergo nonsense mediated mRNA decay. There are 61 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 1-173825319-C-A is Pathogenic according to our data. Variant chr1-173825319-C-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 3776804.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
DARS2	NM_018122.5	c.90C>A	p.Tyr30*	stop_gained	Exon 1 of 17	ENST00000649689.2	NP_060592.2
DARS2	NM_001365212.1	c.90C>A	p.Tyr30*	stop_gained	Exon 1 of 16		NP_001352141.1
DARS2	NM_001365213.2	c.90C>A	p.Tyr30*	stop_gained	Exon 1 of 14		NP_001352142.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
DARS2	ENST00000649689.2	c.90C>A	p.Tyr30*	stop_gained	Exon 1 of 17		NM_018122.5	ENSP00000497569.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1461630 Hom.: 0 Cov.: 30 AF XY: 0.00000138 AC XY: 1 AN XY: 727124

African (AFR) AF: 0.00 AC: 0 AN: 33474

American (AMR) AF: 0.0000224 AC: 1 AN: 44714

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26126

East Asian (EAS) AF: 0.00 AC: 0 AN: 39690

South Asian (SAS) AF: 0.00 AC: 0 AN: 86254

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53368

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111846

Other (OTH) AF: 0.0000331 AC: 2 AN: 60390

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

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

Jan 15, 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 p.Tyr30Ter variant in DARS2 has been reported in two individuals with leukoencephalopathy with brain stem and spinal cord involvement-high lactate syndrome (PMID: 33977142), and has been identified in 0.002% (1/59968) of Admixed American chromosomes by the Genome Aggregation Database (gnomAD, http://gnomad.broadinstitute.org; dbSNP rs959382650). 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 nonsense variant leads to a premature termination codon at position 30, 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 (Richards 2015). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.25
CADD	Pathogenic	34
DANN	Uncertain	0.99
Eigen	Uncertain	0.30
Eigen_PC	Benign	-0.011
FATHMM_MKL	Benign	0.23	N
PhyloP100		1.0
Vest4		0.32
GERP RS		1.6
PromoterAI		-0.011	Neutral
Mutation Taster		=12/188	disease causing (fs/PTC)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

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

Other links and lift over

dbSNP: rs959382650; hg19: chr1-173794457;