chr6-145735429-C-G

Variant names:

• chr6-145735429-C-G
• rs1554269710
• NM_005670.4:c.70G>C

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PM1 PM2 PP3_Moderate

The NM_005670.4(EPM2A):​c.70G>C​(p.Gly24Arg) variant causes a missense change involving the alteration of a non-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 (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G24E) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 33)
• Consequence: EPM2A NM_005670.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 3.43
• Publications: 0 publications found

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]

ENSG00000288551 (HGNC:):

EPM2A-DT (HGNC:48990): (EPM2A divergent transcript)

ACMG classification

Our verdict: Likely_pathogenic. The variant received 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, 13 uncertain in NM_005670.4
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.889

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
EPM2A	NM_005670.4	c.70G>C	p.Gly24Arg	missense_variant	Exon 1 of 4	ENST00000367519.9	NP_005661.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
EPM2A	ENST00000367519.9	c.70G>C	p.Gly24Arg	missense_variant	Exon 1 of 4	1	NM_005670.4	ENSP00000356489.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 34

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Progressive myoclonic epilepsy Uncertain:1

Dec 13, 2017

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces glycine with arginine at codon 24 of the EPM2A protein (p.Gly24Arg). The glycine residue is moderately conserved and there is a moderate physicochemical difference between glycine and arginine. 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. Algorithms developed to predict the effect of missense changes on protein structure and function do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). This variant has not been reported in the literature in individuals with EPM2A-related disease. While this variant is not present in population databases, the frequency information is unreliable, as metrics indicate poor data quality at this position in the ExAC database. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.32	D
BayesDel_noAF	Pathogenic	0.22
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.86	D;.;.;.
Eigen	Uncertain	0.45
Eigen_PC	Uncertain	0.29
FATHMM_MKL	Uncertain	0.88	D
LIST_S2	Benign	0.85	T;T;.;D
M_CAP	Pathogenic	0.91	D
MetaRNN	Pathogenic	0.89	D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.5	M;M;M;M
PhyloP100		3.4
PrimateAI	Pathogenic	0.93	D
PROVEAN	Uncertain	-2.6	D;.;.;.
REVEL	Pathogenic	0.86
Sift	Pathogenic	0.0	D;.;.;.
Sift4G	Pathogenic	0.0	D;D;.;.
Polyphen		1.0	D;D;D;.
Vest4		0.28
MutPred		0.70		Gain of MoRF binding (P = 0.0079);Gain of MoRF binding (P = 0.0079);Gain of MoRF binding (P = 0.0079);Gain of MoRF binding (P = 0.0079);
MVP		0.97
MPC		0.96
ClinPred		1.0	D
GERP RS		2.6
PromoterAI		0.0046	Neutral
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.0
gMVP		0.85
Mutation Taster		=21/79	disease causing

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

Other links and lift over

dbSNP: rs1554269710; hg19: chr6-146056565;