1-99851058-CAG-C

Variant names:

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1PM2PP5_Very_Strong

The NM_000642.3(AGL):c.18_19delGA(p.Gln6HisfsTer20) variant causes a frameshift change. The variant allele was found at a frequency of 0.000144 in 1,613,956 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Likely pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. Q6Q) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.000072 ( 0 hom., cov: 33)

Exomes 𝑓: 0.00015 ( 0 hom. )

Consequence

AGL
NM_000642.3 frameshift

Scores

Not classified

Clinical Significance

Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:12O:1

Conservation

PhyloP100: 5.56

Variant links:

Genes affected

AGL (HGNC:321): (amylo-alpha-1, 6-glucosidase, 4-alpha-glucanotransferase) This gene encodes the glycogen debrancher enzyme which is involved in glycogen degradation. This enzyme has two independent catalytic activities which occur at different sites on the protein: a 4-alpha-glucotransferase activity and a amylo-1,6-glucosidase activity. Mutations in this gene are associated with glycogen storage disease although a wide range of enzymatic and clinical variability occurs which may be due to tissue-specific alternative splicing. Alternatively spliced transcripts encoding different isoforms have been described. [provided by RefSeq, Jul 2008]

AGL links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Pathogenic. Variant got 18 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 285 pathogenic variants in the truncated region.

PM2

Very rare variant in population databases, with high coverage;

PP5

Variant 1-99851058-CAG-C is Pathogenic according to our data. Variant chr1-99851058-CAG-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 195097.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
AGL	NM_000642.3 link	c.18_19delGA	p.Gln6HisfsTer20	frameshift_variant	Exon 2 of 34	ENST00000361915.8	NP_000633.2	P35573-1A0A0S2A4E4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
AGL	ENST00000361915.8 link	c.18_19delGA	p.Gln6HisfsTer20	frameshift_variant	Exon 2 of 34	1	NM_000642.3	ENSP00000355106.3		P35573-1

Frequencies

GnomAD3 genomes

AF:

0.0000723

AC:

AN:

152176

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000241

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:

0.000147

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000437

AC:

AN:

251440

Hom.:

AF XY:

0.0000589

AC XY:

AN XY:

135896

show subpopulations

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:

0.0000967

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.000152

AC:

222

AN:

1461662

Hom.:

AF XY:

0.000144

AC XY:

105

AN XY:

727140

show subpopulations

Gnomad4 AFR exome

AF:

0.0000299

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:

0.000194

Gnomad4 OTH exome

AF:

0.0000828

GnomAD4 genome

AF:

0.0000722

AC:

AN:

152294

Hom.:

Cov.:

AF XY:

0.0000671

AC XY:

AN XY:

74474

show subpopulations

Gnomad4 AFR

AF:

0.0000241

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:

0.000147

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.000130

Hom.:

Bravo

AF:

0.0000907

EpiCase

AF:

0.000218

EpiControl

AF:

0.0000593

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:12Other:1

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Glycogen storage disease type III

Pathogenic:7Other:1

Mar 30, 2024

Baylor Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Apr 27, 2017

Illumina Laboratory Services, Illumina

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The AGL c.18_19delGA (p.Gln6HisfsTer20) variant, also referred to as c.17_18delAG, results in a frameshift, and is predicted to result in premature termination of the protein. The p.Gln6HisfsTer20 variant has been reported in at least three studies in which it is found in a total of 17 patients with glycogen storage disease type III, including in one in a homozygous state, in three in a compound heterozygous state, and in 13 in a heterozygous state where a second variant was not identified (Shen et al. 1996; Goldstein et al. 2010; Hobson-Webb et al. 2010). The p.Gln6HisfsTer20 variant was absent from 20 controls, but is reported at a frequency of 0.00009 in the European (non-Finnish) population of the Exome Aggregation Consortium. Based on the evidence and the potential impact of frameshift variants, the p.Gln6HisfsTer20 variant is classified as likely pathogenic for glycogen storage disease type III. This variant was observed by ICSL as part of a predisposition screen in an ostensibly healthy population. -

Jul 15, 2021

Genome-Nilou Lab

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

GeneReviews

Significance: not provided

Review Status: no classification provided

Collection Method: literature only

Associated with GSD IIIb phenotype -

Sep 16, 2020

Natera, Inc.

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Sep 18, 2017

Knight Diagnostic Laboratories, Oregon Health and Sciences University

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Jan 11, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change creates a premature translational stop signal (p.Gln6Hisfs*20) in the AGL gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in AGL are known to be pathogenic (PMID: 19299494). This variant is present in population databases (rs113994127, gnomAD 0.008%). This premature translational stop signal has been observed in individuals with glycogen storage disease III (PMID: 8755644, 20490926, 20648714). ClinVar contains an entry for this variant (Variation ID: 195097). For these reasons, this variant has been classified as Pathogenic. -

Dec 04, 2019

Myriad Genetics, Inc.

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

NM_000642.2(AGL):c.18_19delGA(Q6Hfs*20) is classified as likely pathogenic in the context of glycogen storage disease type III. Sources cited for classification include the following: PMID 20648714 and 8755644. Classification of NM_000642.2(AGL):c.18_19delGA(Q6Hfs*20) is based on the following criteria: The variant causes a premature termination codon that is expected to be targeted by nonsense-mediated mRNA decay and is reported in individuals with the relevant phenotype. Please note: this variant was assessed in the context of healthy population screening. -

Glycogen storage disease IIIb

Pathogenic:2

Jul 15, 1996

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

Mar 30, 2017

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: The AGL c.18_19delGA (p.Gln6Hisfs) variant results in a premature termination codon, predicted to cause a truncated or absent AGL protein due to nonsense mediated decay, which are commonly known mechanisms for disease. Truncations downstream of this position have been classified as pathogenic by our laboratory (e.g. c.3216_3217delGA/p.Glu1072fs). This variant is absent from 121356 control chromosomes (ExAC dataset). This variant has been reported homozygously and in compound heterozygosity in patients with clinically and biochemically confirmed dx of GSD IIIb (Goldstein_GeneticsMed_2010). In addition, multiple clinical diagnostic laboratories/reputable databases classified this variant as "likely pathogenic/pathogenic". Taken together, this variant is classified as pathogenic. -

not provided

Pathogenic:2

Jun 13, 2014

Eurofins Ntd Llc (ga)

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Feb 09, 2021

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Not observed at a significant frequency in large population cohorts (gnomAD); Frameshift variant predicted to result in protein truncation or nonsense mediated decay in a gene for which loss-of-function is a known mechanism of disease; This variant is associated with the following publications: (PMID: 34820282, 20648714, 30487145, 20301788, 20526204, 20490926, 20071996, 8755644, 31263214, 32222031, 33368379, 31589614) -

AGL-related disorder

Pathogenic:1

May 30, 2024

PreventionGenetics, part of Exact Sciences

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

The AGL c.18_19delGA variant is predicted to result in a frameshift and premature protein termination (p.Gln6Hisfs*20). This sequence variant has been reported to be one of the most common causative variants for glycogen storage disease (GSD) type IIIb (Shen et al. 1996. PubMed ID: 8755644; Goldstein et al. 2010. PubMed ID: 20648714). This variant has also been described in the literature as 17del and c.17_18del. This variant is interpreted as pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

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

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over