rs1554269710

chr6-145735429-C-Achr6-145735429-C-G

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM1 PM2 PP3_Moderate

The NM_005670.4(EPM2A):c.70G>T(p.Gly24Trp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000663 in 150,794 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic 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. G24R) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 33)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: EPM2A NM_005670.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 3.43

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 Likely_pathogenic. Variant got 6 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, 11 uncertain in NM_005670.4
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.875

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
EPM2A	NM_005670.4	c.70G>T	p.Gly24Trp	missense_variant	1/4	ENST00000367519.9
EPM2A-DT	NR_038246.1	n.52+509C>A		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
EPM2A	ENST00000367519.9	c.70G>T	p.Gly24Trp	missense_variant	1/4	1	NM_005670.4	P1

Frequencies

GnomAD3 genomes AF: 0.00000663 AC: 1 AN: 150794 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.0000242

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 1106792 Hom.: 0 Cov.: 34 AF XY: 0.00 AC XY: 0 AN XY: 533866

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: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.00000663 AC: 1 AN: 150794 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 73602

Gnomad4 AFR AF: 0.0000242

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

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 27, 2021

This sequence change replaces glycine with tryptophan at codon 24 of the EPM2A protein (p.Gly24Trp). The glycine residue is moderately conserved and there is a large physicochemical difference between glycine and tryptophan. The frequency data for this variant in the population databases is considered unreliable, as metrics indicate insufficient coverage at this position in the ExAC database. This variant has not been reported in the literature in individuals affected with EPM2A-related conditions. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). 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	Pathogenic	0.36	D
BayesDel_noAF	Pathogenic	0.29
Cadd	Uncertain	25
Dann	Uncertain	0.99
DEOGEN2	Pathogenic	0.86	D;.;.;.
Eigen	Uncertain	0.45
Eigen_PC	Uncertain	0.29
FATHMM_MKL	Uncertain	0.88	D
LIST_S2	Benign	0.81	T;T;.;T
M_CAP	Pathogenic	0.94	D
MetaRNN	Pathogenic	0.87	D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.5	M;M;M;M
MutationTaster	Benign	1.0	D
PrimateAI	Pathogenic	0.93	D
PROVEAN	Uncertain	-3.4	D;.;.;.
REVEL	Pathogenic	0.85
Sift	Pathogenic	0.0	D;.;.;.
Sift4G	Pathogenic	0.0	D;D;.;.
Polyphen		1.0	D;D;D;.
Vest4		0.40
MutPred		0.64		Loss of disorder (P = 0.0018);Loss of disorder (P = 0.0018);Loss of disorder (P = 0.0018);Loss of disorder (P = 0.0018);
MVP		0.99
MPC		0.95
ClinPred		0.99	D
GERP RS		2.6
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.0
gMVP		0.83

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: rs1554269710; hg19: chr6-146056565;