rs1057516328

Positions:

• chr17-80116992-G-A

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PP4 PM3_Supporting PVS1 PM2

This summary comes from the ClinGen Evidence Repository: This variant, c.2214G>A (p.Trp738Ter), is a nonsense variant that is predicted to result in nonsense-mediated decay and lack of gene product, meeting PVS1. The highest population minor allele frequency in gnomAD v2.1.1 is 0.00005 in the East Asian population, meeting PM2. An individual with late onset Pompe disease and meeting the ClinGen LSD VCEP’s specifications for PP4 who is compound heterozygous for the variant and c.-32-13T>G has been reported (PMID 22676651). This data meets PM3_Supporting. In addition, twins meeting PP4 are compound heterozygous for the variant and c.1942G>A (p.Gly648Ser) (PMID 26575883). However, the in trans data from this family will be used in the assessment of p.Gly648Ser and is not included here in order to avoid circular logic. Other cases have been reported but were not included because the residual GAA activity was not reported and therefore PP4 cannot be assessed (PMID 29523196), cDNA nomenclature was not provided (PMID 20033296), or pseudodeficiency alleles were present (PMID 21644219). There is a ClinVar entry for this variant (Variation ID: 370223; 2 star review status) with two 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. ACMG/AMP criteria applied, as specific by the ClinGen LSD VCEP: PVS1, PM2, PM3_Supporting, PP4. LINK:https://erepo.genome.network/evrepo/ui/classification/CA16041901/MONDO:0009290/010

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: GAA NM_000152.5 stop_gained
• Clinical Significance: Pathogenic reviewed by expert panel P:5
• Conservation: PhyloP100: 5.07

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 12 ACMG points.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
GAA	NM_000152.5	c.2214G>A	p.Trp738Ter	stop_gained	16/20	ENST00000302262.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
GAA	ENST00000302262.8	c.2214G>A	p.Trp738Ter	stop_gained	16/20	1	NM_000152.5	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000399 AC: 1 AN: 250908 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135780

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000544

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: 1461468 Hom.: 0 Cov.: 31 AF XY: 0.00000275 AC XY: 2 AN XY: 727042

Gnomad4 AFR exome AF: 0.0000299

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000504

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:5

Revision: reviewed by expert panel

Submissions by phenotype

Glycogen storage disease, type II Pathogenic:5

Likely pathogenic, criteria provided, single submitter	clinical testing	Counsyl	Dec 15, 2015	- -
Pathogenic, reviewed by expert panel	curation	ClinGen Lysosomal Storage Disorder Variant Curation Expert Panel	Oct 05, 2020	This variant, c.2214G>A (p.Trp738Ter), is a nonsense variant that is predicted to result in nonsense-mediated decay and lack of gene product, meeting PVS1. The highest population minor allele frequency in gnomAD v2.1.1 is 0.00005 in the East Asian population, meeting PM2. An individual with late onset Pompe disease and meeting the ClinGen LSD VCEP's specifications for PP4 who is compound heterozygous for the variant and c.-32-13T>G has been reported (PMID 22676651). This data meets PM3_Supporting. In addition, twins meeting PP4 are compound heterozygous for the variant and c.1942G>A (p.Gly648Ser) (PMID 26575883). However, the in trans data from this family will be used in the assessment of p.Gly648Ser and is not included here in order to avoid circular logic. Other cases have been reported but were not included because the residual GAA activity was not reported and therefore PP4 cannot be assessed (PMID 29523196), cDNA nomenclature was not provided (PMID 20033296), or pseudodeficiency alleles were present (PMID 21644219). There is a ClinVar entry for this variant (Variation ID: 370223; 2 star review status) with two 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. ACMG/AMP criteria applied, as specific by the ClinGen LSD VCEP: PVS1, PM2, PM3_Supporting, PP4. -
Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Mar 02, 2023	This sequence change creates a premature translational stop signal (p.Trp738*) 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). This variant is present in population databases (no rsID available, gnomAD 0.006%). This premature translational stop signal has been observed in individual(s) with glycogen storage disease (PMID: 22676651). ClinVar contains an entry for this variant (Variation ID: 370223). For these reasons, this variant has been classified as Pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Oct 25, 2021	Variant summary: GAA c.2214G>A (p.Trp738X) 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 4e-06 in 250908 control chromosomes. c.2214G>A has been reported in the literature in individuals affected with Glycogen Storage Disease, Type 2 (Pompe Disease; Herzog_2012, Zheng_2011, Plockinger_2018). Four 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/likely pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -
Pathogenic, criteria provided, single submitter	curation	Broad Center for Mendelian Genomics, Broad Institute of MIT and Harvard	Jan 22, 2020	The p.Trp738Ter variant in GAA has been reported in 2 Chinese and 2 German individuals with Glycogen Storage Disease II, segregated with disease in 2 affected relatives from 1 family (PMID: 21644219, 22676651), and has also been reported likely pathogenic by Counsyl in ClinVar (Variation ID: 370223). This variant has been identified in 0.005% (1/18392) of East Asian chromosomes by the Genome Aggregation Database (gnomAD, http://gnomad.broadinstitute.org; dbSNP rs1057516328). Although this variant has been seen in the general population, its frequency is low enough to be consistent with a recessive carrier frequency. This nonsense variant leads to a premature termination codon at position 738, which is 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 pathogenic variant, and in individuals with Glycogen Storage Disease II slightly increases the likelihood that the p.Trp738Ter variant is pathogenic (PMID: 22676651). The phenotype of an individual compound heterozygous for this variant is highly specific for Glycogen Storage Disease II based on GAA activity less than 10% of WT, consistent with disease (PMID: 22676651). 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 low frequency in the general population. ACMG/AMP Criteria applied: PVS1, PM3_supporting, PP4, PM2 (Richards 2015). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.51	D
BayesDel_noAF	Pathogenic	0.63
CADD	Pathogenic	45
DANN	Uncertain	1.0
Eigen	Pathogenic	0.79
Eigen_PC	Uncertain	0.65
FATHMM_MKL	Pathogenic	0.99	D
MutationTaster	Benign	1.0	A;A
Vest4		0.94
GERP RS		4.1

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: rs1057516328; hg19: chr17-78090791; COSMIC: COSV104534634; COSMIC: COSV104534634;