chr17-80105132-G-C

Position:

• chr17-80105132-G-C

Variant summary

Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PM2 PP5_Very_Strong

The NM_000152.5(GAA):​c.546G>C​(p.Thr182Thr) variant causes a splice region, synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000689 in 1,451,670 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. T182T) has been classified as Pathogenic.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000069 (0 hom.)
• Consequence: GAA NM_000152.5 splice_region, synonymous
• Scores: Splicing: ADA: 0.9995
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:8
• Conservation: PhyloP100: 0.305

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 10 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 17-80105132-G-C is Pathogenic according to our data. Variant chr17-80105132-G-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 281056.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr17-80105132-G-C is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
GAA	NM_000152.5	c.546G>C	p.Thr182Thr	splice_region_variant, synonymous_variant	2/20	ENST00000302262.8	NP_000143.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
GAA	ENST00000302262.8	c.546G>C	p.Thr182Thr	splice_region_variant, synonymous_variant	2/20	1	NM_000152.5	ENSP00000305692.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000846 AC: 2 AN: 236410 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 130104

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 SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000188

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000689 AC: 10 AN: 1451670 Hom.: 0 Cov.: 36 AF XY: 0.00000832 AC XY: 6 AN XY: 721554

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000902

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:8

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Glycogen storage disease, type II Pathogenic:5

Likely pathogenic, criteria provided, single submitter	clinical testing	Fulgent Genetics, Fulgent Genetics	Nov 22, 2021	- -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Apr 24, 2023	For these reasons, this variant has been classified as Pathogenic. This variant disrupts the c.546G nucleotide in the GAA gene. Other variant(s) that disrupt this nucleotide have been determined to be pathogenic (PMID: 14695532, 21484825, 25037089; Invitae). This suggests that this nucleotide is clinically significant, and that variants that disrupt this position are likely to be disease-causing. Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Studies have shown that this variant results in skipping of skipping of exon 2, and is expected to result in the loss of the initiator methionine (PMID: 31301153). ClinVar contains an entry for this variant (Variation ID: 281056). This variant has been observed in individual(s) with Pompe disease (PMID: 17616415). This variant is present in population databases (no rsID available, gnomAD 0.002%). This sequence change affects codon 182 of the GAA mRNA. It is a 'silent' change, meaning that it does not change the encoded amino acid sequence of the GAA protein. RNA analysis indicates that this variant induces altered splicing and is likely to result in the loss of the initiator methionine. -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Mar 06, 2023	- -
Pathogenic, no assertion criteria provided	clinical testing	Natera, Inc.	Aug 24, 2021	- -
Likely pathogenic, criteria provided, single submitter	curation	Broad Center for Mendelian Genomics, Broad Institute of MIT and Harvard	Jan 22, 2020	The c.546G>C (p.Thr182=) variant in GAA has been reported in 1 Spanish individual with Glycogen Storage Disease II (PMID: 17616415), and has also been reported pathogenic by EGL in ClinVar (Variation ID: 281056). This variant has been identified in 0.002% (2/106330) of European (non-Finnish) chromosomes by the Genome Aggregation Database (gnomAD, http://gnomad.broadinstitute.org; dbSNP rs143523371). Although this variant has been seen in the general population, its frequency is low enough to be consistent with a recessive carrier frequency. This variant is located in the last three bases of the exon, which is part of the 5' splice region. Computational tools do suggest an impact to splicing. The Threonine (Thr) at position 182 is not well conserved in mammals or evolutionary distant species, raising the possibility that a change at this position may be tolerated. However, this information is not predictive enough to determine pathogenicity. The presence of this variant in combination with a pathogenic variant and in an individual with Glycogen Storage Disease II slightly increases the likelihood that the c.546G>C variant is pathogenic (PMID: 17616415). The phenotype of an individual heterozygous for this variant is highly specific for Glycogen Storage Disease II with only 21% of control GAA activity detected in patient fibroblasts (PMID: 17616415). Two additional variants at the same position, c.546G>T and c.546G>A, have been reported as a VUS or likely pathogenic in association with Glycogen Storage Disease II in ClinVar, supporting that a change at this position may not be tolerated (Variation ID: 370637, 280955). In summary, although additional studies are required to fully establish its clinical significance, this variant is likely pathogenic. ACMG/AMP Criteria applied: PM2, PP3, PP4, PM3_Supporting, PM5_Supporting (Richards 2015). -

not provided Pathogenic:3

Likely pathogenic, criteria provided, single submitter	clinical testing	AiLife Diagnostics, AiLife Diagnostics	Oct 19, 2021	- -
Pathogenic, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Jul 06, 2015	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Sep 26, 2022	- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.57
CADD	Benign	19
DANN	Benign	0.79
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.97
SpliceAI score (max)		0.84		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.24		Position offset: 40
DS_DL_spliceai		0.84		Position offset: 0

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs143523371; hg19: chr17-78078931;