6-145627508-C-T

Variant names:

• chr6-145627508-C-T
• rs755742563
• NM_005670.4:c.904G>A

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM1 PM2

The NM_005670.4(EPM2A):​c.904G>A​(p.Ala302Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000821 in 1,461,888 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000082 (0 hom.)
• Consequence: EPM2A NM_005670.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 7.57

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 4 ACMG points.

• PM1: In a domain Tyrosine-protein phosphatase (size 167) in uniprot entity EPM2A_HUMAN there are 10 pathogenic changes around while only 1 benign (91%) in NM_005670.4
• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
EPM2A	NM_005670.4	c.904G>A	p.Ala302Thr	missense_variant	Exon 4 of 4	ENST00000367519.9	NP_005661.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
EPM2A	ENST00000367519.9	c.904G>A	p.Ala302Thr	missense_variant	Exon 4 of 4	1	NM_005670.4	ENSP00000356489.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.0000398 AC: 10 AN: 251370 Hom.: 0 AF XY: 0.0000368 AC XY: 5 AN XY: 135890

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.000289

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: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000821 AC: 12 AN: 1461888 Hom.: 0 Cov.: 32 AF XY: 0.00000825 AC XY: 6 AN XY: 727244

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.000268

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: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

Bravo AF: 0.00000378

ExAC AF: 0.0000330 AC: 4

Asia WGS AF: 0.000289 AC: 1 AN: 3478

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Progressive myoclonic epilepsy Uncertain:1

Aug 25, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) has been performed at Invitae for this missense variant, however the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on EPM2A protein function. ClinVar contains an entry for this variant (Variation ID: 462935). This variant has not been reported in the literature in individuals affected with EPM2A-related conditions. This variant is present in population databases (rs755742563, gnomAD 0.03%). This sequence change replaces alanine, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 302 of the EPM2A protein (p.Ala302Thr). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Benign	-0.13	T
BayesDel_noAF	Benign	-0.13
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Benign	0.29	T;.;.;.;.;.;.;.
Eigen	Benign	0.13
Eigen_PC	Benign	0.11
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.90	D;.;D;.;.;.;.;D
M_CAP	Uncertain	0.086	D
MetaRNN	Uncertain	0.44	T;T;T;T;T;T;T;T
MetaSVM	Uncertain	-0.11	T
MutationAssessor	Uncertain	2.2	M;.;M;.;M;.;.;.
PrimateAI	Benign	0.32	T
PROVEAN	Benign	-1.3	N;.;.;.;.;.;.;.
REVEL	Uncertain	0.46
Sift	Benign	0.089	T;.;.;.;.;.;.;.
Sift4G	Uncertain	0.031	D;.;T;T;.;.;.;.
Polyphen		0.94	P;.;D;.;D;.;.;.
Vest4		0.42
MutPred		0.69		Loss of sheet (P = 0.0104);.;Loss of sheet (P = 0.0104);.;Loss of sheet (P = 0.0104);.;.;.;
MVP		0.89
MPC		0.51
ClinPred		0.51	D
GERP RS		5.2
gMVP		0.61

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: rs755742563; hg19: chr6-145948644;