17-80104815-G-T

Variant names:

• chr17-80104815-G-T
• rs781365881
• NM_000152.5:c.229G>T

Variant summary

Our verdict is Uncertain significance. The variant received 1 ACMG points: 3P and 2B. PM2 PP2 BP4_Moderate

The NM_000152.5(GAA):​c.229G>T​(p.Ala77Ser) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000434 in 1,612,324 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 16/22 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Synonymous variant affecting the same amino acid position (i.e. A77A) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000041 (0 hom.)
• Consequence: GAA NM_000152.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:2
• Conservation: PhyloP100: 0.334
• Publications: 6 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: Uncertain_significance. The variant received 1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• 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.
• BP4: Computational evidence support a benign effect (MetaRNN=0.07751608).

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.229G>T	p.Ala77Ser	missense	Exon 2 of 20	NP_000143.2
	GAA	NM_001079803.3		c.229G>T	p.Ala77Ser	missense	Exon 3 of 21	NP_001073271.1
	GAA	NM_001079804.3		c.229G>T	p.Ala77Ser	missense	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.229G>T	p.Ala77Ser	missense	Exon 2 of 20	ENSP00000305692.3
	GAA	ENST00000390015.7	TSL:1	c.229G>T	p.Ala77Ser	missense	Exon 3 of 21	ENSP00000374665.3
	GAA	ENST00000570803.6	TSL:5	c.229G>T	p.Ala77Ser	missense	Exon 2 of 20	ENSP00000460543.2

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152220 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000147

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.00000405 AC: 1 AN: 247018 AF XY: 0.00000745

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000900

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000411 AC: 6 AN: 1460104 Hom.: 0 Cov.: 31 AF XY: 0.00000551 AC XY: 4 AN XY: 726372

African (AFR) AF: 0.00 AC: 0 AN: 33448

American (AMR) AF: 0.00 AC: 0 AN: 44666

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26108

East Asian (EAS) AF: 0.00 AC: 0 AN: 39646

South Asian (SAS) AF: 0.00 AC: 0 AN: 86180

European-Finnish (FIN) AF: 0.0000192 AC: 1 AN: 52156

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5764

European-Non Finnish (NFE) AF: 0.00000450 AC: 5 AN: 1111788

Other (OTH) AF: 0.00 AC: 0 AN: 60348

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152220 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74360

African (AFR) AF: 0.00 AC: 0 AN: 41468

American (AMR) AF: 0.00 AC: 0 AN: 15292

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3472

East Asian (EAS) AF: 0.00 AC: 0 AN: 5188

South Asian (SAS) AF: 0.00 AC: 0 AN: 4830

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10626

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.0000147 AC: 1 AN: 68026

Other (OTH) AF: 0.00 AC: 0 AN: 2090

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, single submitter

Submissions by phenotype

Glycogen storage disease, type II Uncertain:2

Oct 12, 2021

Natera, Inc.

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: clinical testing

Jun 09, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces alanine, which is neutral and non-polar, with serine, which is neutral and polar, at codon 77 of the GAA protein (p.Ala77Ser). This variant is present in population databases (no rsID available, gnomAD 0.0009%). This variant has not been reported in the literature in individuals affected with GAA-related conditions. ClinVar contains an entry for this variant (Variation ID: 580689). 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 not expected to disrupt GAA protein function. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.081
BayesDel_addAF	Benign	-0.050	T
BayesDel_noAF	Benign	-0.31
CADD	Benign	4.6
DANN	Benign	0.92
DEOGEN2	Benign	0.0065	T
Eigen	Benign	-1.1
Eigen_PC	Benign	-1.0
FATHMM_MKL	Benign	0.16	N
LIST_S2	Benign	0.63	T
M_CAP	Benign	0.038	D
MetaRNN	Benign	0.078	T
MetaSVM	Benign	-0.71	T
MutationAssessor	Benign	0.97	L
PhyloP100		0.33
PrimateAI	Benign	0.40	T
PROVEAN	Benign	0.070	N
REVEL	Benign	0.23
Sift	Benign	0.33	T
Sift4G	Benign	0.31	T
Polyphen		0.035	B
Vest4		0.16
MutPred		0.097		Gain of phosphorylation at A77 (P = 0.0129)
MVP		0.88
MPC		0.10
ClinPred		0.067	T
GERP RS		1.8
Varity_R		0.057
gMVP		0.28
Mutation Taster		=99/1	polymorphism

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: rs781365881; hg19: chr17-78078614;