rs886043343

chr17-80118209-CCA-C

Variant summary

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

The NM_000152.5(GAA):c.2501_2502del(p.Thr834ArgfsTer49) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000205 in 1,460,844 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Pathogenic (★★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: GAA NM_000152.5 frameshift
• Clinical Significance: Pathogenic reviewed by expert panel P:10
• Conservation: PhyloP100: 1.17

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 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 17-80118209-CCA-C is Pathogenic according to our data. Variant chr17-80118209-CCA-C is described in ClinVar as [Pathogenic]. Clinvar id is 286229.Status of the report is reviewed_by_expert_panel, 3 stars. Variant chr17-80118209-CCA-C is described in Lovd as [Pathogenic]. Variant chr17-80118209-CCA-C is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
GAA	NM_000152.5	c.2501_2502del	p.Thr834ArgfsTer49	frameshift_variant	18/20	ENST00000302262.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
GAA	ENST00000302262.8	c.2501_2502del	p.Thr834ArgfsTer49	frameshift_variant	18/20	1	NM_000152.5	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000799 AC: 2 AN: 250190 Hom.: 0 AF XY: 0.00000738 AC XY: 1 AN XY: 135442

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000579

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: 0.00000205 AC: 3 AN: 1460844 Hom.: 0 AF XY: 0.00000138 AC XY: 1 AN XY: 726688

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000448

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: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:10

Revision: reviewed by expert panel

Submissions by phenotype

Glycogen storage disease, type II Pathogenic:8

Pathogenic, criteria provided, single submitter	curation	Broad Center for Mendelian Genomics, Broad Institute of MIT and Harvard	Jan 22, 2020	The p.Thr834ArgfsTer49 variant in GAA has been reported in 8 individuals with Glycogen Storage Disease II (PMID: 22958975, 23601496, 29122469, 19588081), and has also been reported pathogenic by EGL and likely pathogenic by Tehran Medical Genetics Laboratory and Integrated Genetics in ClinVar (Variation ID: 286229). This variant has been identified in 0.0058% (2/34516) of Latino chromosomes by the Genome Aggregation Database (gnomAD, http://gnomad.broadinstitute.org; dbSNP rs886043343). Although this variant has been seen in the general population, its frequency is low enough to be consistent with a recessive carrier frequency. This variant is predicted to cause a frameshift, which alters the protein's amino acid sequence beginning at position 834 and leads to a premature termination codon 49 amino acids downstream. This alteration is then predicted to lead to a truncated or absent protein. Loss of function of the GAA gene is an established disease mechanism in autosomal recessive Glycogen Storage Disease II. The presence of this variant in combination with a reported pathogenic variant and in individuals with Glycogen Storage Disease II increases the likelihood that the p.Thr834ArgfsTer49 variant is pathogenic (PMID: 19588081). The phenotype of individuals heterozygous for this variant is highly specific for Glycogen Storage Disease II based on reduced GAA activity in a dried blood spot or muscle tissue, consistent with disease (PMID: 22958975, 23601496). In summary, this variant meets criteria to be classified as pathogenic for Glycogen Storage Disease II in an autosomal recessive manner based on the predicted impact of the variant and multiple occurrences with pathogenic GAA variants in individuals with Glycogen Storage Disease II. ACMG/AMP Criteria applied: PVS1, PM2, PM3_Supporting, PP4 (Richards 2015). -
Pathogenic, no assertion criteria provided	clinical testing	Counsyl	Nov 17, 2016	- -
Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Jun 04, 2023	This premature translational stop signal has been observed in individuals with Pompe disease (PMID: 19588081, 22958975, 29122469, 30564623). For these reasons, this variant has been classified as Pathogenic. ClinVar contains an entry for this variant (Variation ID: 286229). This variant is present in population databases (no rsID available, gnomAD 0.006%). This sequence change creates a premature translational stop signal (p.Thr834Argfs*49) 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). -
Likely pathogenic, criteria provided, single submitter	clinical testing	Tehran Medical Genetics Laboratory	-	- -
Pathogenic, no assertion criteria provided	clinical testing	Natera, Inc.	Sep 16, 2020	- -
Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Nov 30, 2018	Variant summary: GAA c.2501_2502delCA (p.Thr834ArgfsX49) 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 (eg. c.2544delC, p.Lys849fsX38 and c.2560C>T, p.Arg854X). The variant allele was found at a frequency of 8.1e-06 in 245500 control chromosomes (gnomAD). The variant, c.2501_2502delCA, has been reported in the literature in individuals affected with Glycogen Storage Disease, Type 2 (Pompe Disease)(Kroos_2008, Palermo_2012, Musumeci_2012). These data indicate that the variant is likely to be associated with disease. One clinical diagnostic laboratory has submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation and classified the variant as pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -
Pathogenic, reviewed by expert panel	curation	ClinGen Lysosomal Storage Disorder Variant Curation Expert Panel	May 05, 2020	This variant, c.2501_2502delCA (p.Thr834Argfs) is predicted to result in a frameshift causing a premature termination codon, nonsense medicated decay, and lack of GAA gene product, meeting PVS1. The variant has a highest population minor allele frequency of 0.00005794 in the Latino population, meeting PM2. This variant was found in compound heterozygosity with a known pathogenic variant, c.-32-13T>G, in three patients, who all meet the ClinGen LSD VCEP's PP4 criterion (PMID 22958975). The phase not confirmed in any of these patients. Additional patients with this variant have been reported but were not included because the residual GAA activity was not provided, and therefore PP4 cannot be assessed (PMIDs 19588081, 29122469), or the in trans data had been counted towards another variant and therefore were not included here to avoid circular logic (c.1933G>A (p.Asp645Asn), (PMID 23601496). The data meet PP4 and PM3_Supporting. There is a ClinVar entry for this variant (Variant ID: 286229; 2 star review status) with three submitters classifying the variant as pathogenic and one as likely pathogenic. In summary, this variant meets the criteria to be classified as pathogenic for Pompe disease. GAA-specific ACMG/AMP criteria applied, as specified by the ClinGen LSD VCEP: PVS1, PM2, PM3_Supporting, PP4. -
Pathogenic, criteria provided, single submitter	clinical testing	Fulgent Genetics, Fulgent Genetics	Dec 30, 2021	- -

not provided Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Feb 23, 2016	- -
Pathogenic, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Feb 16, 2021	- -

Computational scores

Source: dbNSFP v4.3

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: rs886043343; hg19: chr17-78092008;