3-49097992-C-A

Position:

• chr3-49097992-C-A

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM2 PP3_Strong

The NM_005051.3(QARS1):​c.2277G>T​(p.Lys759Asn) variant causes a missense, splice region change. The variant allele was found at a frequency of 0.0000131 in 152,194 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: 𝑓 0.000013 (0 hom., cov: 31)
• Consequence: QARS1 NM_005051.3 missense, splice_region
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 6.86

Genes affected

QARS1 (HGNC:9751): (glutaminyl-tRNA synthetase 1) Aminoacyl-tRNA synthetases catalyze the aminoacylation of tRNA by their cognate amino acid. Because of their central role in linking amino acids with nucleotide triplets contained in tRNAs, aminoacyl-tRNA synthetases are thought to be among the first proteins that appeared in evolution. In metazoans, 9 aminoacyl-tRNA synthetases specific for glutamine (gln), glutamic acid (glu), and 7 other amino acids are associated within a multienzyme complex. Although present in eukaryotes, glutaminyl-tRNA synthetase (QARS) is absent from many prokaryotes, mitochondria, and chloroplasts, in which Gln-tRNA(Gln) is formed by transamidation of the misacylated Glu-tRNA(Gln). Glutaminyl-tRNA synthetase belongs to the class-I aminoacyl-tRNA synthetase family. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Jan 2013]

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
QARS1	NM_005051.3	c.2277G>T	p.Lys759Asn	missense_variant, splice_region_variant	23/24	ENST00000306125.12
QARS1	NM_001272073.2	c.2244G>T	p.Lys748Asn	missense_variant, splice_region_variant	23/24
QARS1	XM_017006965.3	c.2151+200G>T		intron_variant
QARS1	NR_073590.2	n.2252G>T		splice_region_variant, non_coding_transcript_exon_variant	23/24

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
QARS1	ENST00000306125.12	c.2277G>T	p.Lys759Asn	missense_variant, splice_region_variant	23/24	1	NM_005051.3	P1

Frequencies

GnomAD3 genomes AF: 0.0000131 AC: 2 AN: 152194 Hom.: 0 Cov.: 31

Gnomad AFR AF: 0.0000483

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

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

GnomAD4 exome Cov.: 30

GnomAD4 genome AF: 0.0000131 AC: 2 AN: 152194 Hom.: 0 Cov.: 31 AF XY: 0.0000135 AC XY: 1 AN XY: 74348

Gnomad4 AFR AF: 0.0000483

Gnomad4 AMR AF: 0.00

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: 0.0000189

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Diffuse cerebral and cerebellar atrophy - intractable seizures - progressive microcephaly syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Aug 13, 2022

This sequence change replaces lysine, which is basic and polar, with asparagine, which is neutral and polar, at codon 759 of the QARS protein (p.Lys759Asn). This variant also falls at the last nucleotide of exon 23, which is part of the consensus splice site for this exon. This variant is present in population databases (no rsID available, gnomAD 0.01%). This variant has not been reported in the literature in individuals affected with QARS-related conditions. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated. Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). 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 available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.24
BayesDel_addAF	Benign	-0.20	T
BayesDel_noAF	Benign	-0.52
CADD	Pathogenic	33
DANN	Uncertain	1.0
DEOGEN2	Benign	0.16	T;.;T
Eigen	Uncertain	0.33
Eigen_PC	Uncertain	0.46
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Uncertain	0.97	D;D;D
M_CAP	Benign	0.013	T
MetaRNN	Benign	0.34	T;T;T
MetaSVM	Benign	-1.1	T
MutationAssessor	Uncertain	2.3	M;.;.
MutationTaster	Benign	1.0	D;D
PrimateAI	Benign	0.34	T
PROVEAN	Uncertain	-2.6	D;D;.
REVEL	Benign	0.092
Sift	Benign	0.031	D;D;.
Sift4G	Uncertain	0.058	T;T;T
Polyphen		0.25	B;.;.
Vest4		0.34
MutPred		0.41		Loss of methylation at K759 (P = 0.0099);.;.;
MVP		0.42
MPC		0.44
ClinPred		0.91	D
GERP RS		5.7
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.40
gMVP		0.48

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	1.0
SpliceAI score (max)		0.82		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.82		Position offset: 0

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

Publications

LitVar

Other links and lift over

dbSNP: rs1324687960; hg19: chr3-49135425;