chr6-145735432-C-G

Position:

• chr6-145735432-C-G

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 4P and 1B. PM1 PM2 BP4

The NM_005670.4(EPM2A):​c.67G>C​(p.Val23Leu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000452 in 1,106,734 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 (★). Synonymous variant affecting the same amino acid position (i.e. V23V) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000045 (0 hom.)
• Consequence: EPM2A NM_005670.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 1.72

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]

EPM2A-DT (HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 3 ACMG points.

• PM1: In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 12 uncertain in NM_005670.4
• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.3232745).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
EPM2A	NM_005670.4	c.67G>C	p.Val23Leu	missense_variant	1/4	ENST00000367519.9
EPM2A-DT	NR_038246.1	n.52+512C>G		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
EPM2A	ENST00000367519.9	c.67G>C	p.Val23Leu	missense_variant	1/4	1	NM_005670.4	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000452 AC: 5 AN: 1106734 Hom.: 0 Cov.: 34 AF XY: 0.00000749 AC XY: 4 AN XY: 533884

Gnomad4 AFR exome AF: 0.0000441

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: 0.00000324

Gnomad4 OTH exome AF: 0.0000233

GnomAD4 genome Cov.: 33

Bravo AF: 0.00000378

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

Aug 10, 2022

This sequence change replaces valine, which is neutral and non-polar, with leucine, which is neutral and non-polar, at codon 23 of the EPM2A protein (p.Val23Leu). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with EPM2A-related conditions. ClinVar contains an entry for this variant (Variation ID: 411295). Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated. 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	Uncertain	0.064	T
BayesDel_noAF	Benign	-0.15
CADD	Benign	17
DANN	Benign	0.72
DEOGEN2	Benign	0.32	T;.;.;.
Eigen	Benign	-0.46
Eigen_PC	Benign	-0.36
FATHMM_MKL	Uncertain	0.83	D
LIST_S2	Benign	0.73	T;T;.;T
M_CAP	Pathogenic	0.90	D
MetaRNN	Benign	0.32	T;T;T;T
MetaSVM	Benign	-0.46	T
MutationAssessor	Benign	1.9	L;L;L;L
MutationTaster	Benign	1.0	N
PrimateAI	Pathogenic	0.93	D
PROVEAN	Benign	-0.050	N;.;.;.
REVEL	Benign	0.18
Sift	Benign	0.59	T;.;.;.
Sift4G	Benign	0.91	T;T;.;.
Polyphen		0.0	B;B;B;.
Vest4		0.053
MutPred		0.35		Loss of sheet (P = 0.0084);Loss of sheet (P = 0.0084);Loss of sheet (P = 0.0084);Loss of sheet (P = 0.0084);
MVP		0.95
MPC		0.24
ClinPred		0.17	T
GERP RS		3.5
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.0
gMVP		0.34

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: rs1060503233; hg19: chr6-146056568;