rs764313717

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM2PP5

The NM_005609.4(PYGM):c.425-26A>G variant causes a intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000122 in 1,612,678 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

Frequency

Genomes: 𝑓 0.000092 ( 0 hom., cov: 32)

Exomes 𝑓: 0.00013 ( 0 hom. )

Consequence

PYGM
NM_005609.4 intron

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:7U:1

Conservation

PhyloP100: 0.0760

Variant links:

Genes affected

PYGM (HGNC:9726): (glycogen phosphorylase, muscle associated) This gene encodes a muscle enzyme involved in glycogenolysis. Highly similar enzymes encoded by different genes are found in liver and brain. Mutations in this gene are associated with McArdle disease (myophosphorylase deficiency), a glycogen storage disease of muscle. Alternative splicing results in multiple transcript variants.[provided by RefSeq, Sep 2009]

PYGM links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Uncertain_significance. Variant got 3 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

PP5

Variant 11-64758375-T-C is Pathogenic according to our data. Variant chr11-64758375-T-C is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 2316.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=5, Pathogenic=1, Uncertain_significance=1}. Variant chr11-64758375-T-C is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
PYGM	NM_005609.4 linkuse as main transcript	c.425-26A>G		intron_variant		ENST00000164139.4
PYGM	NM_001164716.1 linkuse as main transcript	c.244-109A>G		intron_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
PYGM	ENST00000164139.4 linkuse as main transcript	c.425-26A>G		intron_variant		1	NM_005609.4	P1	P11217-1
PYGM	ENST00000377432.7 linkuse as main transcript	c.244-109A>G		intron_variant		2			P11217-2

Frequencies

GnomAD3 genomes

AF:

0.0000921

AC:

AN:

152038

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000242

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:

0.000177

Gnomad OTH

AF:

0.000479

GnomAD3 exomes

AF:

0.0000558

AC:

AN:

250854

Hom.:

AF XY:

0.0000442

AC XY:

AN XY:

135654

show subpopulations

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:

0.000123

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.000125

AC:

183

AN:

1460640

Hom.:

Cov.:

AF XY:

0.000113

AC XY:

AN XY:

726656

show subpopulations

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:

0.000158

Gnomad4 OTH exome

AF:

0.000116

GnomAD4 genome

AF:

0.0000921

AC:

AN:

152038

Hom.:

Cov.:

AF XY:

0.000121

AC XY:

AN XY:

74248

show subpopulations

Gnomad4 AFR

AF:

0.0000242

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.000177

Gnomad4 OTH

AF:

0.000479

Alfa

AF:

0.000174

Hom.:

Bravo

AF:

0.0000982

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:7Uncertain:1

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

Glycogen storage disease, type V

Pathogenic:5Uncertain:1

Uncertain significance, criteria provided, single submitter	clinical testing	Counsyl	Jul 07, 2017	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Knight Diagnostic Laboratories, Oregon Health and Sciences University	Dec 04, 2015	The c.425-26A>G intron variant in the PYGM gene has been previously reported in one affected individual with autosomal recessive McArdle disease who harbored this variant in trans with a second common pathogenic missense variant (G205S). This variant has been shown to result in atypical mild phenotype (Vissing et al., 2009). Splicing studies show this c.425-26A>G variant causes exon skipping of exon 4 in the PYGM gene (Vissing et al., 2009). The c.425-26A>G variant is present at low frequencies (ExAC = 0.006%) or absent in the control population databases (Exome Sequencing Project [ESP] and 1000 Genomes). PYGM is the only gene in which mutations are known to cause McArdle disease. Therefore, this collective evidence supports the classification of the c.425-26A>G as a recessive likely pathogenic variant for McArdle disease. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	May 17, 2023	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Apr 25, 2022	Variant summary: PYGM c.425-26A>G alters a non-conserved nucleotide located at a position not widely known to affect splicing. 4/4 computational tools predict no significant impact on normal splicing. However, at least one publication reports experimental evidence that this variant affects mRNA splicing resulting in skipping of exon 4 (Vissing_2009). The variant allele was found at a frequency of 5.6e-05 in 250854 control chromosomes. This frequency is not significantly higher than estimated for a pathogenic variant in PYGM causing Glycogen Storage Disease, Type V (5.6e-05 vs 0.0035), allowing no conclusion about variant significance. c.425-26A>G has been reported in the literature as a compound heterozygous genotype in individuals affected with Glycogen Storage Disease, Type V (example, Vissing_2009, Gandhi_2021, Pizzamiglio_2021). These data indicate that the variant may be associated with disease. Five clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation (Likely Pathogenic/Pathogenic, n=4; VUS, n=1). Based on the evidence outlined above, the variant was classified as likely pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Jan 25, 2024	This sequence change falls in intron 3 of the PYGM gene. It does not directly change the encoded amino acid sequence of the PYGM protein. RNA analysis indicates that this variant induces altered splicing and may result in an absent or disrupted protein product. This variant is present in population databases (rs764313717, gnomAD 0.01%). This variant has been observed in individual(s) with glycogen storage disease (PMID: 19433441). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. ClinVar contains an entry for this variant (Variation ID: 2316). Studies have shown that this variant results in skipping of exon 4 and introduces a premature termination codon (PMID: 19433441). The resulting mRNA is expected to undergo nonsense-mediated decay. For these reasons, this variant has been classified as Pathogenic. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Oct 20, 2023	- -

McArdle disease, mild

Pathogenic:1

Pathogenic, no assertion criteria provided

literature only

OMIM

Jun 01, 2009

- -

not provided

Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Jul 09, 2021

Canonical splice site variant predicted to result in the skipping of exon 4, however trace amounts of the aberrantly spliced product and residual PYGM activity suggest that the c.425-26A variant is "leaky", allowing some normal spliced product to be generated (Vissing et al., 2009); Not observed at a significant frequency in large population cohorts (Lek et al., 2016); This variant is associated with the following publications: (PMID: 34215481, 19433441, 32075227, 27535533, 25914343, 29754767) -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_noAF

Benign

-0.76

Cadd

Benign

Dann

Benign

0.71

La Branchor

0.89

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.24

Details are displayed if max score is > 0.2

DS_AL_spliceai

0.24

Position offset: -26

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

Publications

LitVar

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over