chr8-1771553-G-A

Position:

• chr8-1771553-G-A

Variant summary

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

The ENST00000331222.6(CLN8):​c.499G>A​(p.Glu167Lys) variant causes a missense change involving the alteration of a 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 (★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: CLN8 ENST00000331222.6 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 9.29

Genes affected

CLN8 (HGNC:2079): (CLN8 transmembrane ER and ERGIC protein) This gene encodes a transmembrane protein belonging to a family of proteins containing TLC domains, which are postulated to function in lipid synthesis, transport, or sensing. The protein localizes to the endoplasmic reticulum (ER), and may recycle between the ER and ER-Golgi intermediate compartment. Mutations in this gene are associated with a disorder characterized by progressive epilepsy with cognitive disabilities (EPMR), which is a subtype of neuronal ceroid lipofuscinoses (NCL). Patients with mutations in this gene have altered levels of sphingolipid and phospholipids in the brain. [provided by RefSeq, Jul 2017]

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PM1: In a domain TLC (size 200) in uniprot entity CLN8_HUMAN there are 39 pathogenic changes around while only 14 benign (74%) in ENST00000331222.6
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.93

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
CLN8	NM_018941.4	c.499G>A	p.Glu167Lys	missense_variant	2/3	ENST00000331222.6	NP_061764.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
CLN8	ENST00000331222.6	c.499G>A	p.Glu167Lys	missense_variant	2/3	1	NM_018941.4	ENSP00000328182	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Neuronal ceroid lipofuscinosis Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Aug 17, 2023

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) performed at Invitae indicates that this missense variant is expected to disrupt CLN8 protein function. ClinVar contains an entry for this variant (Variation ID: 850413). This variant has not been reported in the literature in individuals affected with CLN8-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces glutamic acid, which is acidic and polar, with lysine, which is basic and polar, at codon 167 of the CLN8 protein (p.Glu167Lys). 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
AlphaMissense	Pathogenic	0.98
BayesDel_addAF	Pathogenic	0.47	D
BayesDel_noAF	Pathogenic	0.44
CADD	Pathogenic	30
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.95	D;D;D;D;.;D;.
Eigen	Pathogenic	0.74
Eigen_PC	Pathogenic	0.68
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.96	.;.;.;.;D;.;D
M_CAP	Uncertain	0.25	D
MetaRNN	Pathogenic	0.93	D;D;D;D;D;D;D
MetaSVM	Pathogenic	0.82	D
MutationAssessor	Uncertain	2.6	M;M;M;M;.;M;.
MutationTaster	Benign	1.0	D
PrimateAI	Pathogenic	0.81	D
PROVEAN	Uncertain	-3.9	D;.;.;.;.;.;.
REVEL	Pathogenic	0.95
Sift	Pathogenic	0.0	D;.;.;.;.;.;.
Sift4G	Pathogenic	0.0	D;.;.;.;.;.;D
Polyphen		1.0	D;D;D;D;.;D;.
Vest4		0.97
MutPred		0.77		Gain of solvent accessibility (P = 0.012);Gain of solvent accessibility (P = 0.012);Gain of solvent accessibility (P = 0.012);Gain of solvent accessibility (P = 0.012);Gain of solvent accessibility (P = 0.012);Gain of solvent accessibility (P = 0.012);Gain of solvent accessibility (P = 0.012);
MVP		0.97
MPC		0.30
ClinPred		1.0	D
GERP RS		5.1
Varity_R		0.82
gMVP		0.98

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: rs144495588; hg19: chr8-1719719;