rs1555600061

Variant names:

• chr17-80108512-T-C
• rs1555600061
• NM_000152.5:c.1099T>C

Variant summary

Our verdict is Likely pathogenic. The variant received 9 ACMG points: 9P and 0B. PP3 PM2_Supporting PM3_Strong PS3_Supporting PP4_Moderate

This summary comes from the ClinGen Evidence Repository: The NM_000152.5: c.1099T>C (p.Trp367Arg) variant in GAA is a missense variant with a highest population minor allele frequency in gnomAD v4.0.0 of 0.0000013 (1/761904 alleles) in the European (non-Finnish) population, which is lower than the ClinGen Lysosomal Diseases (LD) VCEP’s threshold for PM2_Supporting (<0.001), meeting this criterion (PM2_Supporting). This variant has been reported in at least 3 patients with a diagnosis of infantile onset Pompe disease (IOPD) with documented deficient GAA activity and/or on enzyme replacement therapy (ERT) (PMID:17056254‚ 22658377, 23787031, 25139343, 31510962); it was also reported in one patient of late-onset Pompe disease (LOPD) (PMID:22958975) (PP4_Moderate). This variant was found to be homozygous in one Spanish-Italian patient with IOPD and was confirmed to be inherited from both parents (PMID:17056254). At least one Hispanic patient with IOPD under ERT (PMID:22658377, 23787031, 25139343) was found to be compound heterozygous (phase unknown) for this variant and c.1802C>T (p.Ser601Leu), a GAA variant classified as pathogenic by the ClinGen LD VCEP. This variant was confirmed to be in trans with c.1942G>A (p.Gly648Ser), a GAA variant classified as pathogenic by the ClinGen LD VCEP, in a Thailand patient with IOPD (PMID:31510962). One Italian patient with LOPD was reported to be compound heterozygous (phase unknown) for the variant and c.-32-13T>G, the most common pathogenic GAA variant associated with LOPD (PMID:22958975) (PM3_Strong). Expression of the variant in COS-7 cells resulted in <2% wild type GAA activity without mature processed GAA protein on immunoblots, indicating a negative impact on GAA function (PMID:19862843) (PS3_Supporting). The computational meta-predictor REVEL has a score of 0.944 for the variant, which is above the threshold of 0.7, indicating a negative impact on GAA function (PP3). Another missense variant, c.1099T>G (p.Trp367Gly), in the same codon has been reported in a patient with LOPD (PMID:29124014). However, the data for p.Trp367Arg will be used in the assessment of p.Trp367Gly and therefore PM5 is not met here in order to avoid circular argument. There is a ClinVar entry for this variant (Variation ID: 555820). In summary, this variant meets the criteria to be classified as likely pathogenic for Pompe disease. GAA-specific ACMG/AMP criteria met, as specified by the ClinGen LD VCEP (Specifications Version 2.0): PM3_Strong, PP4_Moderate, PP3, PS3_Supporting, PM2_Supporting. (Classification approved by the ClinGen LD VCEP, on December 5, 2023). LINK:https://erepo.genome.network/evrepo/ui/classification/CA401364951/MONDO:0009290/010

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: GAA NM_000152.5 missense
• Clinical Significance: Likely pathogenic reviewed by expert panel P:6 U:1
• Conservation: PhyloP100: 7.50
• 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: Likely_pathogenic. The variant received 9 ACMG points.

• PS3: 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.
• PP3: 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.1099T>C	p.Trp367Arg	missense	Exon 7 of 20	NP_000143.2
	GAA	NM_001079803.3		c.1099T>C	p.Trp367Arg	missense	Exon 8 of 21	NP_001073271.1
	GAA	NM_001079804.3		c.1099T>C	p.Trp367Arg	missense	Exon 7 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.1099T>C	p.Trp367Arg	missense	Exon 7 of 20	ENSP00000305692.3
	GAA	ENST00000390015.7	TSL:1	c.1099T>C	p.Trp367Arg	missense	Exon 8 of 21	ENSP00000374665.3
	GAA	ENST00000570803.6	TSL:5	c.1099T>C	p.Trp367Arg	missense	Exon 7 of 20	ENSP00000460543.2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.85e-7 AC: 1 AN: 1460828 Hom.: 0 Cov.: 39 AF XY: 0.00 AC XY: 0 AN XY: 726736

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

American (AMR) AF: 0.00 AC: 0 AN: 44706

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26124

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86256

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 52466

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5766

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1111960

Other (OTH) AF: 0.00 AC: 0 AN: 60374

GnomAD4 genome Cov.: 33

ClinVar

ClinVar submissions as Germline

Significance: Likely pathogenic

Revision: reviewed by expert panel

Pathogenic	VUS	Benign	Condition
5	1	-	Glycogen storage disease, type II (6)
1	-	-	not provided (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.95
BayesDel_addAF	Pathogenic	0.55	D
BayesDel_noAF	Pathogenic	0.55
CADD	Pathogenic	30
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.98	D
Eigen	Pathogenic	0.89
Eigen_PC	Pathogenic	0.78
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.95	D
M_CAP	Pathogenic	0.78	D
MetaRNN	Pathogenic	1.0	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	4.5	H
PhyloP100		7.5
PrimateAI	Uncertain	0.75	T
PROVEAN	Pathogenic	-14	D
REVEL	Pathogenic	0.94
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.99
MutPred		0.96		Gain of methylation at W367 (P = 0.0123)
MVP		1.0
MPC		0.72
ClinPred		1.0	D
GERP RS		4.8
Varity_R		0.98
gMVP		0.98
Mutation Taster		=1/99	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: rs1555600061; hg19: chr17-78082311;