6-145627439-G-A

Position:

• chr6-145627439-G-A

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_005670.4(EPM2A):​c.973C>T​(p.Arg325Cys) variant causes a missense change. The variant allele was found at a frequency of 0.00000547 in 1,461,868 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 12/19 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R325H) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000055 (0 hom.)
• Consequence: EPM2A NM_005670.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 4.45

Genes affected

EPM2A (HGNC:3413): (EPM2A glucan phosphatase, laforin) This gene encodes a dual-specificity phosphatase and may be involved in the regulation of glycogen metabolism. The protein acts on complex carbohydrates to prevent glycogen hyperphosphorylation, thus avoiding the formation of insoluble aggregates. Loss-of-function mutations in this gene have been associated with Lafora disease, a rare, adult-onset recessive neurodegenerative disease, which results in myoclonus epilepsy and usually results in death several years after the onset of symptoms. The disease is characterized by the accumulation of insoluble particles called Lafora bodies, which are derived from glycogen. [provided by RefSeq, Jan 2018]

ACMG classification

Verdict is Uncertain_significance. Variant got 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.23756671).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
EPM2A	NM_005670.4	c.973C>T	p.Arg325Cys	missense_variant	4/4	ENST00000367519.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
EPM2A	ENST00000367519.9	c.973C>T	p.Arg325Cys	missense_variant	4/4	1	NM_005670.4	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000795 AC: 2 AN: 251464 Hom.: 0 AF XY: 0.0000147 AC XY: 2 AN XY: 135904

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: 0.0000327

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000879

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000547 AC: 8 AN: 1461868 Hom.: 0 Cov.: 32 AF XY: 0.00000963 AC XY: 7 AN XY: 727240

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: 0.0000348

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000450

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

Bravo AF: 0.00000378

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Progressive myoclonic epilepsy Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Nov 20, 2019

This sequence change replaces arginine with cysteine at codon 325 of the EPM2A protein (p.Arg325Cys). The arginine residue is moderately conserved and there is a large physicochemical difference between arginine and cysteine. This variant is present in population databases (rs746413047, ExAC 0.006%). This variant has not been reported in the literature in individuals with EPM2A-related conditions. Algorithms developed to predict the effect of missense changes on protein structure and function output the following: SIFT: "Deleterious"; PolyPhen-2: "Benign"; Align-GVGD: "Class C0". The cysteine amino acid residue is found in multiple mammalian species, suggesting that this missense change does not adversely affect protein function. These predictions have not been confirmed by published functional studies and their clinical significance is uncertain. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Benign	-0.019	T
BayesDel_noAF	Benign	-0.17
CADD	Benign	22
DANN	Benign	0.95
DEOGEN2	Benign	0.28	T;.;.;.;.;.
Eigen	Benign	-0.60
Eigen_PC	Benign	-0.48
FATHMM_MKL	Uncertain	0.93	D
LIST_S2	Benign	0.78	T;.;.;.;.;T
M_CAP	Benign	0.067	D
MetaRNN	Benign	0.24	T;T;T;T;T;T
MetaSVM	Benign	-0.37	T
MutationAssessor	Benign	1.6	L;.;.;.;.;.
MutationTaster	Benign	0.98	N
PrimateAI	Benign	0.23	T
PROVEAN	Uncertain	-2.4	N;.;.;.;.;.
REVEL	Uncertain	0.31
Sift	Benign	0.096	T;.;.;.;.;.
Sift4G	Benign	0.11	T;.;T;.;.;.
Polyphen		0.010	B;.;.;.;.;.
Vest4		0.18
MutPred		0.49		Loss of MoRF binding (P = 2e-04);.;.;.;.;.;
MVP		0.95
MPC		0.32
ClinPred		0.35	T
GERP RS		3.1
gMVP		0.63

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		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: rs746413047; hg19: chr6-145948575; COSMIC: COSV100837564; COSMIC: COSV100837564;