rs113994129

chr1-99881329-G-A

Variant summary

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

The NM_000642.3(AGL):c.2039G>A(p.Trp680Ter) variant causes a stop gained change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000805 in 1,613,932 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: 𝑓 0.000020 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000068 (0 hom.)
• Consequence: AGL NM_000642.3 stop_gained
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:12 O:1
• Conservation: PhyloP100: 9.17

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]

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 1-99881329-G-A is Pathogenic according to our data. Variant chr1-99881329-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 1096.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
AGL	NM_000642.3	c.2039G>A	p.Trp680Ter	stop_gained	16/34	ENST00000361915.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
AGL	ENST00000361915.8	c.2039G>A	p.Trp680Ter	stop_gained	16/34	1	NM_000642.3	P1

Frequencies

GnomAD3 genomes AF: 0.0000197 AC: 3 AN: 152162 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

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: 0.0000441

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.00000798 AC: 2 AN: 250658 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135498

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: 0.0000177

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000684 AC: 10 AN: 1461770 Hom.: 0 Cov.: 33 AF XY: 0.00000688 AC XY: 5 AN XY: 727180

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000224

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: 0.00000809

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.0000197 AC: 3 AN: 152162 Hom.: 0 Cov.: 32 AF XY: 0.0000269 AC XY: 2 AN XY: 74332

Gnomad4 AFR AF: 0.00

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: 0.0000441

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000322 Hom.: 0

Bravo AF: 0.0000113

ExAC AF: 0.0000165 AC: 2

EpiCase AF: 0.0000545

EpiControl AF: 0.0000593

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:12 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Glycogen storage disease type III Pathogenic:8 Other:1

Pathogenic, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Jun 23, 2022	- -
Pathogenic, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Jul 15, 2021	- -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Oct 12, 2023	- -
not provided, no classification provided	literature only	GeneReviews	-	2039G>A, 2590C>T and 3682C>T are 3 common variants that together account for approximately 28% of pathogenic variants in persons of European origin. -
Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Jan 11, 2018	Variant summary: The AGL c.2039G>A (p.Trp680X) 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. A truncation downstream of this position has been classified as pathogenic by our laboratory (c.2929C>T, p.Arg977X). One in silico tool predicts a damaging outcome for this variant. One functional study showed no GSD residual activity in GSD IIIa patients homozygous for this variant in leukocytes, fibroblasts, and/or liver tissue, and/or muscle tissue (Sentner_2012). This variant was found in 2/245574 control chromosomes in gnomAD at a frequency of 0.0000081, which does not exceed the estimated maximal expected allele frequency of a pathogenic AGL variant (0.0022822).This variant has been reported in 4 homozygous patients of Caribbean origin with GSD IIIa (Sentner_2012) and also in one patient diagnosed with GSD type IIIb in compound heterozygosity with AGL c.16C>T (p.Gln6Ter)( Shen_AGL_JCI_1996). In addition, multiple clinical diagnostic laboratories/reputable databases classified this variant as pathogenic. Taken together, this variant is classified as pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Fulgent Genetics, Fulgent Genetics	Dec 27, 2021	- -
Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Jan 29, 2024	This sequence change creates a premature translational stop signal (p.Trp680*) 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 (rs113994129, gnomAD 0.002%). This premature translational stop signal has been observed in individual(s) with glycogen storage disease type III (GSDIII) (PMID: 8755644, 23430490). ClinVar contains an entry for this variant (Variation ID: 1096). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Institute of Human Genetics Munich, Klinikum Rechts Der Isar, TU München	Jun 09, 2020	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Institute of Human Genetics, University of Leipzig Medical Center	Jan 01, 2019	- -

not provided Pathogenic:3

Pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Jun 26, 2017	The W680X nonsense variant in the AGL gene has been reported previously in association with glycogen storage disease type IIIb in an individual compound heterozygous with a pathogenic variant on the opposite allele (Shen et al., 1996). However, W680X has also been reported in four homozygous individuals with hepatomegaly, mild or no cardiac involvement, mild skeletal myopathy, and elevated CK levels, suggesting more of a type IIIa phenotype (Sentner et al., 2013). This pathogenic variant is predicted to cause loss of normal protein function either through protein truncation or nonsense-mediated mRNA decay. Therefore, W680X is interpreted to be pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	AiLife Diagnostics, AiLife Diagnostics	Feb 09, 2022	- -
Pathogenic, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Jun 13, 2014	- -

Glycogen storage disease IIIb Pathogenic:1

Pathogenic, no assertion criteria provided

literature only

OMIM

Jul 15, 1996

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.61	D
BayesDel_noAF	Pathogenic	0.66
Cadd	Pathogenic	41
Dann	Uncertain	1.0
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.93
FATHMM_MKL	Pathogenic	0.99	D
MutationTaster	Benign	1.0	A;A;A;A;A;A;A
Vest4		0.97
GERP RS		5.7

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.050		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: rs113994129; hg19: chr1-100346885;