17-80107866-G-T

Variant names:

• chr17-80107866-G-T
• rs543300039
• NM_000152.5:c.925G>T

Variant summary

Our verdict is Pathogenic. The variant received 13 ACMG points: 13P and 0B. PM1 PM2 PM5 PP2 PP3_Strong PP5_Moderate

The NM_000152.5(GAA):​c.925G>T​(p.Gly309Trp) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000685 in 1,459,274 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 13/22 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G309R) has been classified as Pathogenic.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: GAA NM_000152.5 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 7.93
• Publications: 0 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 13 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 6 uncertain in NM_000152.5
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr17-80107866-G-A is described in ClinVar as [Pathogenic]. Clinvar id is 188797.Status of the report is reviewed_by_expert_panel, 3 stars.
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 201 curated pathogenic missense variants (we use a threshold of 10). The gene has 50 curated benign missense variants. Gene score misZ: -0.63308 (below the threshold of 3.09). Trascript score misZ: -0.32889 (below the threshold of 3.09). GenCC associations: The gene is linked to glycogen storage disease due to acid maltase deficiency, infantile onset, glycogen storage disease II, glycogen storage disease due to acid maltase deficiency, late-onset.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.971
• PP5: Variant 17-80107866-G-T is Pathogenic according to our data. Variant chr17-80107866-G-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 2729477.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
GAA	NM_000152.5	c.925G>T	p.Gly309Trp	missense_variant	Exon 5 of 20	ENST00000302262.8	NP_000143.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GAA	ENST00000302262.8	c.925G>T	p.Gly309Trp	missense_variant	Exon 5 of 20	1	NM_000152.5	ENSP00000305692.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.85e-7 AC: 1 AN: 1459274 Hom.: 0 Cov.: 53 AF XY: 0.00 AC XY: 0 AN XY: 725920

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 33446

American (AMR) AF: 0.00 AC: 0 AN: 44590

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26098

East Asian (EAS) AF: 0.00 AC: 0 AN: 39644

South Asian (SAS) AF: 0.00 AC: 0 AN: 86130

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 52070

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5382

European-Non Finnish (NFE) AF: 9.00e-7 AC: 1 AN: 1111676

Other (OTH) AF: 0.00 AC: 0 AN: 60238

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000000), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 33

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Glycogen storage disease, type II Pathogenic:1

Jun 25, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant disrupts the p.Gly309 amino acid residue in GAA. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 9660056, 16917947, 17210890, 17616415, 23601496, 24245577, 24495340, 29122469). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt GAA protein function. This sequence change replaces glycine, which is neutral and non-polar, with tryptophan, which is neutral and slightly polar, at codon 309 of the GAA protein (p.Gly309Trp). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with GAA-related conditions. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.98
BayesDel_addAF	Pathogenic	0.54	D
BayesDel_noAF	Pathogenic	0.54
CADD	Pathogenic	30
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.98	D;D
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.88
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Uncertain	0.97	.;D
M_CAP	Pathogenic	0.83	D
MetaRNN	Pathogenic	0.97	D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	4.4	H;H
PhyloP100		7.9
PrimateAI	Pathogenic	0.86	D
PROVEAN	Pathogenic	-7.4	D;D
REVEL	Pathogenic	0.92
Sift	Pathogenic	0.0	D;D
Sift4G	Pathogenic	0.0	D;D
Polyphen		1.0	D;D
Vest4		0.94
MutPred		0.74		Gain of sheet (P = 0.0477);Gain of sheet (P = 0.0477);
MVP		0.99
MPC		0.59
ClinPred		1.0	D
GERP RS		5.3
Varity_R		0.95
gMVP		0.97
Mutation Taster		=8/92	disease causing

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: rs543300039; hg19: chr17-78081665; COSMIC: COSV100163190; COSMIC: COSV100163190;