20-25276731-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2 PP3_Moderate

The NM_002862.4(PYGB):c.746C>T(p.Ala249Val) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: not found (cov: 33)
• Consequence: PYGB NM_002862.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 7.82

Genes affected

PYGB (HGNC:9723): (glycogen phosphorylase B) The protein encoded by this gene is a glycogen phosphorylase found predominantly in the brain. The encoded protein forms homodimers which can associate into homotetramers, the enzymatically active form of glycogen phosphorylase. The activity of this enzyme is positively regulated by AMP and negatively regulated by ATP, ADP, and glucose-6-phosphate. This enzyme catalyzes the rate-determining step in glycogen degradation. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.898

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
PYGB	NM_002862.4	c.746C>T	p.Ala249Val	missense_variant	6/20	ENST00000216962.9
PYGB	XM_047440342.1	c.746C>T	p.Ala249Val	missense_variant	6/16

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
PYGB	ENST00000216962.9	c.746C>T	p.Ala249Val	missense_variant	6/20	1	NM_002862.4	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Mar 11, 2022

The c.746C>T (p.A249V) alteration is located in exon 6 (coding exon 6) of the PYGB gene. This alteration results from a C to T substitution at nucleotide position 746, causing the alanine (A) at amino acid position 249 to be replaced by a valine (V). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.91
BayesDel_addAF	Pathogenic	0.32	D
BayesDel_noAF	Pathogenic	0.23
Cadd	Pathogenic	29
Dann	Pathogenic	1.0
DEOGEN2	Uncertain	0.68	D
Eigen	Uncertain	0.65
Eigen_PC	Uncertain	0.57
FATHMM_MKL	Uncertain	0.90	D
LIST_S2	Pathogenic	0.99	D
M_CAP	Pathogenic	0.30	D
MetaRNN	Pathogenic	0.90	D
MetaSVM	Pathogenic	0.92	D
MutationAssessor	Pathogenic	3.0	M
MutationTaster	Benign	1.0	D
PrimateAI	Uncertain	0.69	T
PROVEAN	Uncertain	-3.4	D
REVEL	Pathogenic	0.82
Sift	Uncertain	0.0010	D
Sift4G	Uncertain	0.0020	D
Polyphen		1.0	D
Vest4		0.86
MutPred		0.67		Loss of ubiquitination at K248 (P = 0.1099);
MVP		0.96
MPC		0.78
ClinPred		0.99	D
GERP RS		3.5
Varity_R		0.90
gMVP		0.81

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.040		Details are displayed if max score is > 0.2

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

Publications

LitVar

Other links and lift over

dbSNP: rs2088315341; hg19: chr20-25257367;