11-64754026-C-T

Variant names:

• chr11-64754026-C-T
• rs1163710370
• NM_005609.4:c.1093-1G>A

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PVS1_Moderate PM2

The NM_005609.4(PYGM):​c.1093-1G>A variant causes a splice acceptor, intron change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000691 in 1,448,088 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: PYGM NM_005609.4 splice_acceptor, intron
• Scores: Splicing: ADA: 0.9999
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 7.91
• Publications: 0 publications found

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 Gene-Disease associations (from GenCC):

• glycogen storage disease V

  Inheritance: AR, AD Classification: DEFINITIVE, STRONG, SUPPORTIVE, LIMITED Submitted by: ClinGen, Ambry Genetics, Orphanet, Labcorp Genetics (formerly Invitae), Genomics England PanelApp

ACMG classification

Our verdict: Uncertain_significance. The variant received 4 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.05812574 fraction of the gene. Cryptic splice site detected, with MaxEntScore 3.2, offset of 1, new splice context is: tgcccaccccgtgtgccaAGcgt. Cryptic site results in frameshift change. If cryptic site found is not functional and variant results in exon loss, it results in inframe change.
• PM2: Very rare variant in population databases, with high coverage

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_005609.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	PYGM	NM_005609.4	MANE Select	c.1093-1G>A		splice_acceptor intron	N/A	NP_005600.1	P11217-1
	PYGM	NM_001164716.1		c.829-1G>A		splice_acceptor intron	N/A	NP_001158188.1	P11217-2

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	PYGM	ENST00000164139.4	TSL:1 MANE Select	c.1093-1G>A		splice_acceptor intron	N/A	ENSP00000164139.3	P11217-1
	PYGM	ENST00000967737.1		c.1192-1G>A		splice_acceptor intron	N/A	ENSP00000637796.1
	PYGM	ENST00000938870.1		c.1009-1G>A		splice_acceptor intron	N/A	ENSP00000608929.1

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome AF: 6.91e-7 AC: 1 AN: 1448088 Hom.: 0 Cov.: 37 AF XY: 0.00000139 AC XY: 1 AN XY: 719032

⚠️ 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: 33210

American (AMR) AF: 0.00 AC: 0 AN: 42600

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25874

East Asian (EAS) AF: 0.00 AC: 0 AN: 39044

South Asian (SAS) AF: 0.00 AC: 0 AN: 84356

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 51914

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5746

European-Non Finnish (NFE) AF: 9.05e-7 AC: 1 AN: 1105420

Other (OTH) AF: 0.00 AC: 0 AN: 59924

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 31

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.34	D
BayesDel_noAF	Pathogenic	0.25
CADD	Pathogenic	35
DANN	Uncertain	0.99
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.84
FATHMM_MKL	Pathogenic	1.0	D
PhyloP100		7.9
GERP RS		4.8
Mutation Taster		=0/100	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.91
SpliceAI score (max)		1.0		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.93		Position offset: -2
DS_AL_spliceai		1.0		Position offset: -1

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

Other links and lift over

dbSNP: rs1163710370; hg19: chr11-64521498;