1-173850408-G-T

Position:

• chr1-173850408-G-T

Variant summary

Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PVS1 PM2

The NM_018122.5(DARS2):​c.1273G>T​(p.Glu425*) 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 1,461,750 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 Uncertain significance (★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 30)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: DARS2 NM_018122.5 stop_gained
• Clinical Significance: Uncertain significance criteria provided, single submitter P:3 U:1
• Conservation: PhyloP100: 1.18

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 (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 10 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

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
DARS2	NM_018122.5	c.1273G>T	p.Glu425*	stop_gained	13/17	ENST00000649689.2	NP_060592.2
DARS2	NM_001365213.2	c.1273G>T	p.Glu425*	stop_gained	13/14		NP_001352142.1
DARS2	NM_001365212.1	c.1192-2941G>T		intron_variant			NP_001352141.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
DARS2	ENST00000649689.2	c.1273G>T	p.Glu425*	stop_gained	13/17		NM_018122.5	ENSP00000497569.1

Frequencies

GnomAD3 genomes Cov.: 30

GnomAD3 exomes AF: 0.00000796 AC: 2 AN: 251328 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135860

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

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: 0.0000176

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1461750 Hom.: 0 Cov.: 35 AF XY: 0.00000138 AC XY: 1 AN XY: 727164

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: 0.00000270

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 30

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Pathogenic:3 Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Pathogenic:2

Pathogenic, no assertion criteria provided	clinical testing	Joint Genome Diagnostic Labs from Nijmegen and Maastricht, Radboudumc and MUMC+	-	- -
Pathogenic, no assertion criteria provided	clinical testing	Laboratory of Diagnostic Genome Analysis, Leiden University Medical Center (LUMC)	-	- -

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

Pathogenic, no assertion criteria provided	literature only	OMIM	Apr 01, 2007	- -
Uncertain significance, criteria provided, single submitter	curation	Broad Center for Mendelian Genomics, Broad Institute of MIT and Harvard	Sep 04, 2024	The p.Glu425Ter variant in DARS2 has been reported in at least 2 individuals, in the compound heterozygous state, with leukoencephalopathy with brain stem and spinal cord involvement-high lactate syndrome (PMID: 17384640, 33977142), and has been identified in 0.0003% (3/1179944) of European (non-Finnish) chromosomes by the Genome Aggregation Database (gnomAD, http://gnomad.broadinstitute.org; dbSNP rs121918211). Although this variant has been seen in the general population in the heterozygous state, its frequency is low enough to be consistent with a recessive carrier frequency. However, this variant has only been reported in individuals while also in cis with another pathogenic variant, and therefore it is unknown whether it is disease causing in isolation. This variant has also been reported in ClinVar (Variation ID: 1065) and has been interpreted as Pathogenic by OMIM, Laboratory of Diagnostic Genome Analysis, Leiden University Medical Center (LUMC), and Joint Genome Diagnostic Labs from Nijmegen and Maastricht (Radboudumc and MUMC+). This nonsense variant leads to a premature termination codon at position 425, 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, while there is some suspicion for a pathogenic role, the clinical significance of this variant is uncertain. ACMG/AMP Criteria applied: PVS1, PM2_supporting (Richards 2015). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.61	D
BayesDel_noAF	Pathogenic	0.29
CADD	Pathogenic	34
DANN	Uncertain	0.98
Eigen	Uncertain	0.28
Eigen_PC	Benign	-0.024
FATHMM_MKL	Benign	0.18	N
Vest4		0.73
GERP RS		4.8

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

Publications

LitVar

Other links and lift over

dbSNP: rs121918211; hg19: chr1-173819546;