rs1555600575

Positions:

• chr17-80110056-G-A

Variant summary

Our verdict is Likely pathogenic. Variant got 9 ACMG points: 9P and 0B. PM2_Supporting PVS1_Strong PP4_Moderate PM3

This summary comes from the ClinGen Evidence Repository: This variant, c.1437+1G>A, alters the donor splice site of intron 9. Based on RT-PCR results from a patient who is compound heterozygous for the variant, this results in skipping of exon 9, which leads to an in frame deletion of p.Asp443_Lys479del (PMID 22676651), including part of the GAA catalytic barrel (PMID 22253258). Western blot analysis of protein extracted from cultured skin fibroblasts from a patient who is homozygous for the variant revealed that the patient was positive from cross-reactive immunological material, supporting that the variant results in an in-frame consequence (PMID 22252923). Based on these results, PVS1_Strong was applied. The highest population minor allele frequency in gnomAD v2.1.1 is 0.00003 in the Latino population, meeting PM2_Supporting. Two patients with Pompe disease have been reported who are homozygous for the variant and meet the ClinGen LSD VCEP's PP4 specifications (PMID 22555271, 22252923; personal communication), meeting PM3 and PP4_Moderate. Another patient has been reported with the variant in trans with c.1076-22G>A (PMID 22676651). In trans data from this patient will be used in the assessment of c.1076-22G>A and is not included here in order to avoid a circular argument. There is a ClinVar entry for this variant (Variation ID: 555864; two star review status) with five submitters classifying the variant as pathogenic and one submitter classifying as likely pathogenic. In summary, this variant meets the criteria to be classified as likely pathogenic for Pompe disease. GAA-specific ACMG/AMP criteria applied, as specified by the ClinGen LSD VCEP (Specifications Version 2.0): PVS1_Strong, PM2_Supporting, PM3, PP4_Moderate. LINK:https://erepo.genome.network/evrepo/ui/classification/CA401366675/MONDO:0009290/010

• Frequency:
  • Genomes: not found (cov: 34)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: GAA NM_000152.5 splice_donor, intron
• Scores: Splicing: ADA: 0.9999
• Clinical Significance: Likely pathogenic reviewed by expert panel P:8
• Conservation: PhyloP100: 9.23

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 Likely_pathogenic. Variant got 9 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.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
GAA	NM_000152.5	c.1437+1G>A		splice_donor_variant, intron_variant		ENST00000302262.8	NP_000143.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
GAA	ENST00000302262.8	c.1437+1G>A		splice_donor_variant, intron_variant		1	NM_000152.5	ENSP00000305692.3

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD3 exomes AF: 0.00000403 AC: 1 AN: 248246 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135114

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000290

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: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000206 AC: 3 AN: 1459796 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 726284

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000224

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: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 34

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:8

Revision: reviewed by expert panel

Submissions by phenotype

Glycogen storage disease, type II Pathogenic:6

Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Apr 10, 2021	Variant summary: GAA c.1437+1G>A is located in a canonical splice-site and is predicted to affect mRNA splicing resulting in a significantly altered protein due to either exon skipping, shortening, or inclusion of intronic material. Several computational tools predict a significant impact on normal splicing: Four predict the variant abolishes a 5' splicing donor site. However, these predictions have yet to be confirmed by functional studies. The variant allele was found at a frequency of 4e-06 in 248246 control chromosomes. c.1437+1G>A has been reported in the literature in individuals affected with Glycogen Storage Disease, Type 2 (Pompe Disease) (example, Reuser_2019). These data indicate that the variant is likely to be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Two clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. All laboratories classified the variant as pathogenic/likely pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -
Likely pathogenic, criteria provided, single submitter	curation	Broad Center for Mendelian Genomics, Broad Institute of MIT and Harvard	Jan 22, 2020	The c.1437+1G>A variang in GAA has been reported in 4 individuals with glycogen storage disease II (PMID: 22555271, 28266734, 22676651, 22252923) and has been reported in ClinVar as pathogenic by Counsyl (VariationID: 555864). This variant has been identified in 0.003% (1/34538) Latino chromosomes by the Genome Aggregation Database (gnomAD, http://gnomad.broadinstitute.org; dbSNP rs1555600575). Although this variant has been seen in the general population, its frequency is low enough to be consistent with a recessive carrier frequency. In vitro functional studies using an expression vector system demonstrating abnormal splicing provide some evidence that the c.1437+1G>A variant may impact protein function (PMID: 11343339). This variant occurs in the invariant region (+/- 1/2) of the splice consensus sequence and is predicted to cause skipping of exon 9 leading to an absent protein (PMID: 22676651, 22252923, 11343339). Loss of function of the GAA gene is an established disease mechanism in autosomal recessive glycogen storage disease II. In summary, although additional studies are required to fully establish its clinical significance, this variant is likely pathogenic. ACMG/AMP Criteria applied: PVS1_strong, PM2 (Richards 2015). -
Pathogenic, criteria provided, single submitter	clinical testing	Counsyl	Dec 29, 2017	- -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Dec 02, 2023	This sequence change affects a donor splice site in intron 9 of the GAA gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in GAA are known to be pathogenic (PMID: 18425781, 22252923). This variant is not present in population databases (gnomAD no frequency). Disruption of this splice site has been observed in individuals with Pompe disease (PMID: 11343339, 18429042, 22252923). ClinVar contains an entry for this variant (Variation ID: 555864). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. -
Likely pathogenic, reviewed by expert panel	curation	ClinGen Lysosomal Storage Disorder Variant Curation Expert Panel	May 16, 2023	This variant, c.1437+1G>A, alters the donor splice site of intron 9. Based on RT-PCR results from a patient who is compound heterozygous for the variant, this results in skipping of exon 9, which leads to an in frame deletion of p.Asp443_Lys479del (PMID 22676651), including part of the GAA catalytic barrel (PMID 22253258). Western blot analysis of protein extracted from cultured skin fibroblasts from a patient who is homozygous for the variant revealed that the patient was positive from cross-reactive immunological material, supporting that the variant results in an in-frame consequence (PMID 22252923). Based on these results, PVS1_Strong was applied. The highest population minor allele frequency in gnomAD v2.1.1 is 0.00003 in the Latino population, meeting PM2_Supporting. Two patients with Pompe disease have been reported who are homozygous for the variant and meet the ClinGen LSD VCEP's PP4 specifications (PMID 22555271, 22252923; personal communication), meeting PM3 and PP4_Moderate. Another patient has been reported with the variant in trans with c.1076-22G>A (PMID 22676651). In trans data from this patient will be used in the assessment of c.1076-22G>A and is not included here in order to avoid a circular argument. There is a ClinVar entry for this variant (Variation ID: 555864; two star review status) with five submitters classifying the variant as pathogenic and one submitter classifying as likely pathogenic. In summary, this variant meets the criteria to be classified as likely pathogenic for Pompe disease. GAA-specific ACMG/AMP criteria applied, as specified by the ClinGen LSD VCEP (Specifications Version 2.0): PVS1_Strong, PM2_Supporting, PM3, PP4_Moderate. -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Mar 10, 2023	- -

not provided Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Mar 15, 2024	Canonical splice site variant resulting in an in-frame loss of the adjacent exon in a gene for which loss of function is a known mechanism of disease (PMID: 22676651); Not observed at significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 22252923, 23430949, 11343339, 33073027, 19343043, 22253258, 31342611, 22676651, 33073007, 18429042, 22555271, 28266734) -
Pathogenic, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Jul 07, 2023	- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.22
CADD	Pathogenic	27
DANN	Uncertain	0.99
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	0.93
FATHMM_MKL	Pathogenic	1.0	D
GERP RS		5.4
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		2.8

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.95
SpliceAI score (max)		1.0		Details are displayed if max score is > 0.2
DS_DL_spliceai		1.0		Position offset: -1

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

Publications

LitVar

Other links and lift over

dbSNP: rs1555600575; hg19: chr17-78083855; COSMIC: COSV56409771; COSMIC: COSV56409771;