chr4-177438779-C-T

Variant names:

• chr4-177438779-C-T
• rs745976989
• NM_000027.4:c.473G>A

Variant summary

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

The NM_000027.4(AGA):​c.473G>A​(p.Trp158*) variant causes a stop gained change. The variant allele was found at a frequency of 0.00000274 in 1,457,642 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 (★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000027 (0 hom.)
• Consequence: AGA NM_000027.4 stop_gained
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 6.62

Genes affected

AGA (HGNC:318): (aspartylglucosaminidase) This gene encodes a member of the N-terminal nucleophile (Ntn) hydrolase family of proteins. The encoded preproprotein is proteolytically processed to generate alpha and beta chains that comprise the mature enzyme. This enzyme is involved in the catabolism of N-linked oligosaccharides of glycoproteins. It cleaves asparagine from N-acetylglucosamines as one of the final steps in the lysosomal breakdown of glycoproteins. Mutations in this gene are associated with the lysosomal storage disease aspartylglycosaminuria that results in progressive neurodegeneration. Alternative splicing results in multiple transcript variants, at least one of which encodes an isoform that is subject to proteolytic processing. [provided by RefSeq, Nov 2015]

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 4-177438779-C-T is Pathogenic according to our data. Variant chr4-177438779-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 370266.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
AGA	NM_000027.4	c.473G>A	p.Trp158*	stop_gained	Exon 4 of 9	ENST00000264595.7	NP_000018.2
AGA	NM_001171988.2	c.473G>A	p.Trp158*	stop_gained	Exon 4 of 9		NP_001165459.1
AGA	XM_047449722.1	c.473G>A	p.Trp158*	stop_gained	Exon 4 of 7		XP_047305678.1
AGA	NR_033655.2	n.535G>A		non_coding_transcript_exon_variant	Exon 4 of 8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
AGA	ENST00000264595.7	c.473G>A	p.Trp158*	stop_gained	Exon 4 of 9	1	NM_000027.4	ENSP00000264595.2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000796 AC: 2 AN: 251336 Hom.: 0 AF XY: 0.0000147 AC XY: 2 AN XY: 135862

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000578

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: 0.00

GnomAD4 exome AF: 0.00000274 AC: 4 AN: 1457642 Hom.: 0 Cov.: 29 AF XY: 0.00000414 AC XY: 3 AN XY: 725434

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000447

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: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Aspartylglucosaminuria Pathogenic:2

Feb 04, 2023

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: 370266). This variant has not been reported in the literature in individuals affected with AGA-related conditions. This variant is present in population databases (rs745976989, gnomAD 0.006%). This sequence change creates a premature translational stop signal (p.Trp158*) in the AGA gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in AGA are known to be pathogenic (PMID: 7627186, 11309371). -

Dec 30, 2015

Counsyl

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.50	D
BayesDel_noAF	Pathogenic	0.66
CADD	Pathogenic	40
DANN	Uncertain	1.0
Eigen	Pathogenic	0.94
Eigen_PC	Pathogenic	0.83
FATHMM_MKL	Pathogenic	0.98	D
Vest4		0.97
ClinPred		1.0	D
GERP RS		5.7

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.020		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: rs745976989; hg19: chr4-178359933;