4-177433252-A-C

Position:

• chr4-177433252-A-C

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM1 PM2 PP3_Moderate

The NM_000027.4(AGA):​c.902T>G​(p.Phe301Cys) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000123 in 1,461,768 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 (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. F301S) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.000012 (0 hom.)
• Consequence: AGA NM_000027.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 8.65

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 Likely_pathogenic. Variant got 6 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 3 uncertain in NM_000027.4
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.927

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
AGA	NM_000027.4	c.902T>G	p.Phe301Cys	missense_variant	8/9	ENST00000264595.7
AGA	NM_001171988.2	c.872T>G	p.Phe291Cys	missense_variant	8/9
AGA	NR_033655.2	n.888T>G		non_coding_transcript_exon_variant	7/8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
AGA	ENST00000264595.7	c.902T>G	p.Phe301Cys	missense_variant	8/9	1	NM_000027.4	P1
AGA	ENST00000502310.5			downstream_gene_variant		5

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.0000358 AC: 9 AN: 251432 Hom.: 0 AF XY: 0.0000221 AC XY: 3 AN XY: 135886

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000867

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: 0.0000528

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000123 AC: 18 AN: 1461768 Hom.: 0 Cov.: 31 AF XY: 0.0000110 AC XY: 8 AN XY: 727176

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000894

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: 0.0000126

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

Bravo AF: 0.0000151

ExAC AF: 0.0000412 AC: 5

EpiCase AF: 0.00

EpiControl AF: 0.000178

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

CeGaT Center for Human Genetics Tuebingen

May 01, 2016

- -

Aspartylglucosaminuria Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Dec 07, 2023

This sequence change replaces phenylalanine, which is neutral and non-polar, with cysteine, which is neutral and slightly polar, at codon 301 of the AGA protein (p.Phe301Cys). This variant is present in population databases (rs35916166, gnomAD 0.009%). This variant has not been reported in the literature in individuals affected with AGA-related conditions. ClinVar contains an entry for this variant (Variation ID: 809706). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt AGA protein function with a negative predictive value of 80%. 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	Uncertain	0.45
BayesDel_addAF	Pathogenic	0.25	D
BayesDel_noAF	Pathogenic	0.31
CADD	Pathogenic	27
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.73	D
Eigen	Pathogenic	0.69
Eigen_PC	Pathogenic	0.72
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.96	D
M_CAP	Uncertain	0.12	D
MetaRNN	Pathogenic	0.93	D
MetaSVM	Uncertain	0.37	D
MutationAssessor	Uncertain	2.5	M
MutationTaster	Benign	1.0	D
PrimateAI	Uncertain	0.58	T
PROVEAN	Uncertain	-4.0	D
REVEL	Pathogenic	0.83
Sift	Benign	0.18	T
Sift4G	Benign	0.19	T
Polyphen		0.96	D
Vest4		0.91
MVP		0.97
MPC		0.55
ClinPred		0.72	D
GERP RS		6.0
Varity_R		0.80
gMVP		0.97

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: rs35916166; hg19: chr4-178354406;