NM_000152.5:c.258dupC

Variant names:

• chr17-80104837-T-TC
• rs761317813
• NM_000152.5:c.258dupC

Variant summary

Our verdict is Pathogenic. Variant got 13 ACMG points: 13P and 0B. PP4_Moderate PVS1 PM3 PM2_Supporting

This summary comes from the ClinGen Evidence Repository: The NM_000152.5:c.258dup (p.Asn87GlnfsTer9) variant in GAA is a frameshift variant predicted to cause a premature stop codon in biologically-relevant-exon 2/20, leading to nonsense mediated decay in a gene in which loss-of-function is an established disease mechanism (PVS1). At least 10 patients with this variant and reported to have Pompe disease have been reported. This includes two patients with documented laboratory values showing GAA deficiency meeting the ClinGen LSD VCEP’s specifications for PP4_Moderate; one of them on enzyme replacement therapy (PMID 21484825, 31467850), a further 7, at least, patients on enzyme replacement therapy, without documented values for GAA activity, meeting specifications for PP4 (PMID 26873529, 31086307, 31392188, 31676142, 32248831), and additional patients with insufficient details to meet the requirements for PP4 (PMID 10206684, 16917947, 29961517, 30564623). At least 7 patients are compound heterozygous for the variant and a pathogenic variant, c.-32-13T>G, in GAA (PM3). Another two patients are compound heterozygous for the variant and either c.1195-8G>A (PMID 21484825) or c.1115A>T (p.His372Leu) (PMID 31467850). The in trans data from both of these patients will be used in the assessment of the other variant and is, therefore, not included here in order to avoid circular logic. The variant is absent in gnomAD v2.1.1 (PM2_Supporting). There is a ClinVar entry for this variant (Variation ID: 282842, 2 star review status) with five submitters classifying the variant as pathogenic. In summary, this variant meets the criteria to be classified as pathogenic for Pompe disease. GAA-specific GAA criteria met, as specified by the ClinGen LSD VCEP (Specification Version 2.0): PVS1, PM3, PP4_Moderate, PM2_Supporting. LINK:https://erepo.genome.network/evrepo/ui/classification/CA8814826/MONDO:0009290/010

• Frequency:
  • Genomes: 𝑓 0.000033 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000054 (0 hom.)
• Consequence: GAA NM_000152.5 frameshift
• Clinical Significance: Pathogenic reviewed by expert panel P:12
• Conservation: PhyloP100: -0.512

Genes affected

GAA (HGNC:4065): (alpha glucosidase) This gene encodes lysosomal alpha-glucosidase, which is essential for the degradation of glycogen to glucose in lysosomes. The encoded preproprotein is proteolytically processed to generate multiple intermediate forms and the mature form of the enzyme. Defects in this gene are the cause of glycogen storage disease II, also known as Pompe's disease, which is an autosomal recessive disorder with a broad clinical spectrum. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Jan 2016]

ACMG classification

Verdict is Pathogenic. Variant got 13 ACMG points.

• PVS1: For more information check the summary or visit ClinGen Evidence Repository.
• PM2: For more information check the summary or visit ClinGen Evidence Repository.
• PM3: For more information check the summary or visit ClinGen Evidence Repository.
• PP4: For more information check the summary or visit ClinGen Evidence Repository.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
GAA	NM_000152.5	c.258dupC	p.Asn87GlnfsTer9	frameshift_variant	Exon 2 of 20	ENST00000302262.8	NP_000143.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GAA	ENST00000302262.8	c.258dupC	p.Asn87GlnfsTer9	frameshift_variant	Exon 2 of 20	1	NM_000152.5	ENSP00000305692.3

Frequencies

GnomAD3 genomes AF: 0.0000330 AC: 5 AN: 151632 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000243

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: 0.0000589

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 0.0000541 AC: 79 AN: 1459916 Hom.: 0 Cov.: 31 AF XY: 0.0000468 AC XY: 34 AN XY: 726320

Gnomad4 AFR exome AF: 0.0000598

Gnomad4 AMR exome AF: 0.0000224

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000116

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000639

Gnomad4 OTH exome AF: 0.0000663

GnomAD4 genome AF: 0.0000330 AC: 5 AN: 151632 Hom.: 0 Cov.: 32 AF XY: 0.0000270 AC XY: 2 AN XY: 74006

Gnomad4 AFR AF: 0.0000243

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: 0.0000589

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000712 Hom.: 0

Bravo AF: 0.0000189

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:12

Revision: reviewed by expert panel

Submissions by phenotype

Glycogen storage disease, type II Pathogenic:7

Nov 11, 2024

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.Asn87Glnfs*9) in the GAA gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in GAA are known to be pathogenic (PMID: 18425781, 22252923). The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This premature translational stop signal has been observed in individuals with glycogen storage disease II (PMID: 10206684, 16917947, 21484825). ClinVar contains an entry for this variant (Variation ID: 282842). For these reasons, this variant has been classified as Pathogenic. -

Jan 22, 2020

Broad Center for Mendelian Genomics, Broad Institute of MIT and Harvard

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: curation

The heterozygous p.Asn87GlnfsTer9 variant in GAA has been reported in 5 individuals (including 1 from the UK and 1 Italian individual) with Glycogen Storage Disease II (PMID: 16917947, 26873529, 21484825, 10206684), and has also been reported pathogenic by EGL Genetic Diagnostics and Invitae in ClinVar (Variation ID: 282842). Data from large population studies is insufficient to assess the frequency of this variant. This variant is predicted to cause a frameshift, which alters the protein's amino acid sequence beginning at position 87 and leads to a premature termination codon 9 amino acids downstream. This alteration is then predicted to lead to a truncated or absent protein. Loss of function of the GAA gene is a moderately established disease mechanism in autosomal recessive Glycogen Storage Disease II. The presence of this variant in combination with a pathogenic variant and in an individual with Glycogen Storage Disease II increases the likelihood that the p.Asn87GlnfsTer9 variant is pathogenic (PMID: 26873529). The phenotype of an individual heterozygous for this variant is highly specific for Glycogen Storage Disease II with less than 5% of normal GAA activity detected in their fibroblasts (PMID: 21484825, 26873529). In summary, this variant meets criteria to be classified as pathogenic for Glycogen Storage Disorder II in an autosomal recessive manner based on the predicted impact of the variant and an occurrence with a pathogenic GAA variant in an individual with Glycogen Storage Disorder II. ACMG/AMP Criteria applied: PVS1, PM3_Supporting, PP4 (Richards 2015). -

Sep 28, 2021

ClinGen Lysosomal Storage Disorder Variant Curation Expert Panel

Significance: Pathogenic

Review Status: reviewed by expert panel

Collection Method: curation

The NM_000152.5:c.258dup (p.Asn87GlnfsTer9) variant in GAA is a frameshift variant predicted to cause a premature stop codon in biologically-relevant-exon 2/20, leading to nonsense mediated decay in a gene in which loss-of-function is an established disease mechanism (PVS1). At least 10 patients with this variant and reported to have Pompe disease have been reported. This includes two patients with documented laboratory values showing GAA deficiency meeting the ClinGen LSD VCEP’s specifications for PP4_Moderate; one of them on enzyme replacement therapy (PMID 21484825, 31467850), a further 7, at least, patients on enzyme replacement therapy, without documented values for GAA activity, meeting specifications for PP4 (PMID 26873529, 31086307, 31392188, 31676142, 32248831), and additional patients with insufficient details to meet the requirements for PP4 (PMID 10206684, 16917947, 29961517, 30564623). At least 7 patients are compound heterozygous for the variant and a pathogenic variant, c.-32-13T>G, in GAA (PM3). Another two patients are compound heterozygous for the variant and either c.1195-8G>A (PMID 21484825) or c.1115A>T (p.His372Leu) (PMID 31467850). The in trans data from both of these patients will be used in the assessment of the other variant and is, therefore, not included here in order to avoid circular logic. The variant is absent in gnomAD v2.1.1 (PM2_Supporting). There is a ClinVar entry for this variant (Variation ID: 282842, 2 star review status) with five submitters classifying the variant as pathogenic. In summary, this variant meets the criteria to be classified as pathogenic for Pompe disease. GAA-specific GAA criteria met, as specified by the ClinGen LSD VCEP (Specification Version 2.0): PVS1, PM3, PP4_Moderate, PM2_Supporting. -

Sep 16, 2020

Natera, Inc.

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Feb 09, 2020

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

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: GAA c.258dupC (p.Asn87GlnfsX9) results in a premature termination codon, predicted to cause a truncation of the encoded protein or absence of the 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. The variant allele was found at a frequency of 1.2e-05 in 246016 control chromosomes. c.258dupC has been reported in the literature in individuals affected with Glycogen Storage Disease, Type 2 (Pompe Disease) (example, Beesley_1998, Montalvo_2006, Bali_2011, Nallamilli_2018, Kishnani_2019). These data indicate that the variant is likely to be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Two clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. All laboratories classified the variant as pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -

Nov 21, 2023

Baylor Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Nov 12, 2021

Fulgent Genetics, Fulgent Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

not provided Pathogenic:4

-

Genome Diagnostics Laboratory, Amsterdam University Medical Center

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

-

Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Aug 18, 2015

Eurofins Ntd Llc (ga)

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Sep 16, 2022

Revvity Omics, Revvity

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

GAA-related disorder Pathogenic:1

Jul 30, 2024

PreventionGenetics, part of Exact Sciences

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

The GAA c.258dupC variant is predicted to result in a frameshift and premature protein termination (p.Asn87Glnfs*9). This variant has been repeatedly reported in individuals with Pompe disease (see for example: Beesley et al. 1997. PubMed ID: 10206684; Nallamilli et al. 2018. PubMed ID: 30564623; Kishnani et al. 2019. PubMed ID: 31086307; Lee et al. 2019. PubMed ID: 31467850; Bali et al. 2011. PubMed ID: 21484825). Measured GAA activity for patients harboring this variant was demonstrated to be significantly decreased compared to normal (Bali et al. 2011. PubMed ID: 21484825; Lee et al. 2019. PubMed ID: 31467850). This variant is reported in 0.0041% of alleles in individuals of African descent in gnomAD. Frameshift variants in GAA are expected to be pathogenic, and this variant has been interpreted as pathogenic by the ClinGen Lysosomal Storage Disorder Variant Curation Expert Panel (https://www.ncbi.nlm.nih.gov/clinvar/variation/282842/). This variant is interpreted as pathogenic. -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs761317813; hg19: chr17-78078636;