chr17-80104963-GGT-G

Variant names:

• chr17-80104963-GGT-G
• rs1207988953
• NM_000152.5:c.379_380delTG

Variant summary

Our verdict is Pathogenic. The variant received 15 ACMG points: 15P and 0B. PM2_Supporting PM3_Strong PP4_Moderate PVS1

This summary comes from the ClinGen Evidence Repository: NM_000152.5:c.379_380del (p.Cys127LeufsTer18) 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 4 patients with Pompe disease and this variant have been reported that meet the ClinGen LSD VCEP’s specifications for PP4_Moderate. Of these patients, the available data includes documentation of laboratory values showing GAA deficiency (PMIDs 18757064, 24245577, 24715333, 30049495, 33162552). Furthermore, one of these patients had documented features consistent with infantile onset Pompe disease (PMID 24715333, 33162552) and another was on enzyme replacement therapy (PMID 30049495)(PP4_Moderate). These patients are all compound heterozygous for the variant and another pathogenic variant in GAA, phase unknown, including c.525delT (PMID 24715333, 33162552), “del exon 18” (PMID 9660056), and c.-32-13T>G (PMID 17573812, 17643989, 18757064, 24245577, 33458579; at least two patients). Total 2 points (PM3_Strong). Another patients is compound heterozygous for the variant and c.2104C>T (p.Arg702Cys); phase unconfirmed (PMID 30049495). The in trans data from this patient will be used in the assessment of p.Arg702Cys and was 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: 552747, two star review status) with two submitters classifying the variant as pathogenic. In summary, this variant meets the criteria to be classified as pathogenic for Pompe disease. GAA-specific ACMG/AMP criteria met, as specified by the ClinGen LSD VCEP Specification Version 2.0): PVS1, PM3_Strong, PP4_Moderate, PM2_Supporting. LINK:https://erepo.genome.network/evrepo/ui/classification/CA658795227/MONDO:0009290/010

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000055 (0 hom.)
• Consequence: GAA NM_000152.5 frameshift
• Clinical Significance: Pathogenic reviewed by expert panel P:7
• Conservation: PhyloP100: 9.57
• Publications: 2 publications found

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]

GAA Gene-Disease associations (from GenCC):

• glycogen storage disease II

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Genomics England PanelApp, Laboratory for Molecular Medicine, Labcorp Genetics (formerly Invitae), PanelApp Australia, ClinGen, G2P
• glycogen storage disease due to acid maltase deficiency, infantile onset

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• glycogen storage disease due to acid maltase deficiency, late-onset

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 15 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.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000152.5. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GAA	NM_000152.5	MANE Select	c.379_380delTG	p.Cys127LeufsTer18	frameshift	Exon 2 of 20	NP_000143.2
	GAA	NM_001079803.3		c.379_380delTG	p.Cys127LeufsTer18	frameshift	Exon 3 of 21	NP_001073271.1
	GAA	NM_001079804.3		c.379_380delTG	p.Cys127LeufsTer18	frameshift	Exon 2 of 20	NP_001073272.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GAA	ENST00000302262.8	TSL:1 MANE Select	c.379_380delTG	p.Cys127LeufsTer18	frameshift	Exon 2 of 20	ENSP00000305692.3
	GAA	ENST00000390015.7	TSL:1	c.379_380delTG	p.Cys127LeufsTer18	frameshift	Exon 3 of 21	ENSP00000374665.3
	GAA	ENST00000570803.6	TSL:5	c.379_380delTG	p.Cys127LeufsTer18	frameshift	Exon 2 of 20	ENSP00000460543.2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000548 AC: 8 AN: 1460220 Hom.: 0 AF XY: 0.00000688 AC XY: 5 AN XY: 726416

African (AFR) AF: 0.00 AC: 0 AN: 33476

American (AMR) AF: 0.00 AC: 0 AN: 44690

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26134

East Asian (EAS) AF: 0.00 AC: 0 AN: 39666

South Asian (SAS) AF: 0.00 AC: 0 AN: 86244

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 52032

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00000720 AC: 8 AN: 1111848

Other (OTH) AF: 0.00 AC: 0 AN: 60362

GnomAD4 genome Cov.: 33

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000378

ClinVar

ClinVar submissions as Germline

Significance: Pathogenic

Revision: reviewed by expert panel

Pathogenic	VUS	Benign	Condition
5	-	-	Glycogen storage disease, type II (5)
2	-	-	not provided (2)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		9.6
Mutation Taster		=0/200	disease causing (ClinVar)

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

Other links and lift over

dbSNP: rs1207988953; hg19: chr17-78078762;