8-1780317-G-T

Variant names:

• chr8-1780317-G-T
• rs386834134
• NM_018941.4:c.611G>T

Variant summary

Our verdict is Pathogenic. The variant received 11 ACMG points: 11P and 0B. PM1 PM2 PM5 PP3_Strong PP5

The NM_018941.4(CLN8):​c.611G>T​(p.Arg204Leu) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000274 in 1,461,890 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 Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R204C) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000027 (0 hom.)
• Consequence: CLN8 NM_018941.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:2 U:1
• Conservation: PhyloP100: 7.37
• Publications: 5 publications found

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]

CLN8 Gene-Disease associations (from GenCC):

• neuronal ceroid lipofuscinosis

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
• neuronal ceroid lipofuscinosis 8

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Genomics England PanelApp, G2P, Orphanet, Ambry Genetics, Myriad Women’s Health
• neuronal ceroid lipofuscinosis 8 northern epilepsy variant

  Inheritance: AR Classification: STRONG, SUPPORTIVE Submitted by: Genomics England PanelApp, Orphanet
• autism spectrum disorder

  Inheritance: AD Classification: NO_KNOWN Submitted by: Ambry Genetics

KBTBD11-OT1 (HGNC:):

ACMG classification

Our verdict: Pathogenic. The variant received 11 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 16 uncertain in NM_018941.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr8-1780316-C-T is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 2804.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.976
• PP5: Variant 8-1780317-G-T is Pathogenic according to our data. Variant chr8-1780317-G-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 56715.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_018941.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CLN8	NM_018941.4	MANE Select	c.611G>T	p.Arg204Leu	missense	Exon 3 of 3	NP_061764.2

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CLN8	ENST00000331222.6	TSL:1 MANE Select	c.611G>T	p.Arg204Leu	missense	Exon 3 of 3	ENSP00000328182.4
	KBTBD11-OT1	ENST00000635855.1	TSL:5	n.543+8720G>T		intron	N/A	ENSP00000489726.1
	CLN8	ENST00000519254.2	TSL:5	c.611G>T	p.Arg204Leu	missense	Exon 3 of 3	ENSP00000490016.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD2 exomes AF: 0.00000398 AC: 1 AN: 251312 AF XY: 0.00

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000880

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000274 AC: 4 AN: 1461890 Hom.: 0 Cov.: 32 AF XY: 0.00000275 AC XY: 2 AN XY: 727246

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53416

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00000360 AC: 4 AN: 1112012

Other (OTH) AF: 0.00 AC: 0 AN: 60396

GnomAD4 genome Cov.: 33

Alfa AF: 0.00000995 Hom.: 0

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:2 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Neuronal ceroid lipofuscinosis 8 Pathogenic:1

Juha Muilu Group; Institute for Molecular Medicine Finland (FIMM)

Significance: Likely pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

Neuronal ceroid lipofuscinosis Pathogenic:1

Oct 14, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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. This variant disrupts the p.Arg204 amino acid residue in CLN8. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 15024724, 25326637; Invitae). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. ClinVar contains an entry for this variant (Variation ID: 56715). This missense change has been observed in individual(s) with neuronal ceroid lipofuscinosis (PMID: 19807737). This variant is present in population databases (rs386834134, gnomAD 0.0009%). This sequence change replaces arginine, which is basic and polar, with leucine, which is neutral and non-polar, at codon 204 of the CLN8 protein (p.Arg204Leu). In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic.

not specified Uncertain:1

Jun 20, 2023

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: CLN8 c.611G>T (p.Arg204Leu) results in a non-conservative amino acid change located in the TRAM/LAG1/CLN8 homology domain (IPR006634) of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 4e-06 in 251312 control chromosomes (gnomAD). c.611G>T has been reported in the literature in the homozygous state in one individual affected with Neuronal Ceroid-Lipofuscinosis (Reinhardt_2010). These data indicate that the variant may be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publication has been ascertained in the context of this evaluation (PMID: 19807737). One submitter has provided a clinical-significance assessment for this variant to ClinVar after 2014 and has classified the variant as likely pathogenic. Based on the evidence outlined above, the variant was classified as VUS-possibly pathogenic.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.98
BayesDel_addAF	Pathogenic	0.55	D
BayesDel_noAF	Pathogenic	0.55
CADD	Pathogenic	29
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.95	D
Eigen	Pathogenic	0.81
Eigen_PC	Pathogenic	0.76
FATHMM_MKL	Pathogenic	0.98	D
M_CAP	Pathogenic	0.77	D
MetaRNN	Pathogenic	0.98	D
MetaSVM	Pathogenic	0.99	D
MutationAssessor	Uncertain	2.6	M
PhyloP100		7.4
PrimateAI	Uncertain	0.66	T
PROVEAN	Pathogenic	-4.9	D
REVEL	Pathogenic	0.94
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.89
MutPred		0.80		Loss of methylation at R204 (P = 0.0643)
MVP		0.98
MPC		0.31
ClinPred		1.0	D
GERP RS		4.3
Varity_R		0.64
gMVP		0.98
Mutation Taster		=11/89	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: rs386834134; hg19: chr8-1728483; COSMIC: COSV100486070;