rs748862167

chr18-23534544-C-Achr18-23534544-C-T

Variant summary

Our verdict is Pathogenic. Variant got 11 ACMG points: 11P and 0B. PM1 PM2 PM5 PP3_Strong PP5

The NM_000271.5(NPC1):c.3493G>T(p.Val1165Leu) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,528 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. V1165M) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: NPC1 NM_000271.5 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:1
• Conservation: PhyloP100: 7.89

Genes affected

NPC1 (HGNC:7897): (NPC intracellular cholesterol transporter 1) This gene encodes a large protein that resides in the limiting membrane of endosomes and lysosomes and mediates intracellular cholesterol trafficking via binding of cholesterol to its N-terminal domain. It is predicted to have a cytoplasmic C-terminus, 13 transmembrane domains, and 3 large loops in the lumen of the endosome - the last loop being at the N-terminus. This protein transports low-density lipoproteins to late endosomal/lysosomal compartments where they are hydrolized and released as free cholesterol. Defects in this gene cause Niemann-Pick type C disease, a rare autosomal recessive neurodegenerative disorder characterized by over accumulation of cholesterol and glycosphingolipids in late endosomal/lysosomal compartments.[provided by RefSeq, Aug 2009]

ACMG classification

Verdict is Pathogenic. Variant got 11 ACMG points.

• PM1: In a hotspot region, there are 7 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 5 uncertain in NM_000271.5
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr18-23534544-C-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 195723.We mark this variant Likely_pathogenic, oryginal submissions are: {Pathogenic=2, Uncertain_significance=1}.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.982
• PP5: Variant 18-23534544-C-A is Pathogenic according to our data. Variant chr18-23534544-C-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 1501415.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=1, Uncertain_significance=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
NPC1	NM_000271.5	c.3493G>T	p.Val1165Leu	missense_variant	23/25	ENST00000269228.10

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
NPC1	ENST00000269228.10	c.3493G>T	p.Val1165Leu	missense_variant	23/25	1	NM_000271.5	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000399 AC: 1 AN: 250836 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135602

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000544

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: 6.84e-7 AC: 1 AN: 1461528 Hom.: 0 Cov.: 30 AF XY: 0.00 AC XY: 0 AN XY: 727062

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000252

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

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Niemann-Pick disease, type C1 Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Invitae

Jan 11, 2024

This sequence change replaces valine, which is neutral and non-polar, with leucine, which is neutral and non-polar, at codon 1165 of the NPC1 protein (p.Val1165Leu). This variant is present in population databases (rs748862167, gnomAD 0.006%). This variant has not been reported in the literature in individuals affected with NPC1-related conditions. ClinVar contains an entry for this variant (Variation ID: 1501415). 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 NPC1 protein function with a positive predictive value of 95%. This variant disrupts the p.Val1165 amino acid residue in NPC1. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 11349231, 23430855, 26666848). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. 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

Uncertain significance, criteria provided, single submitter

clinical testing

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

Oct 03, 2023

Variant summary: NPC1 c.3493G>T (p.Val1165Leu) results in a conservative amino acid change in the encoded protein sequence. Four 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 250836 control chromosomes (gnomAD). The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.3493G>T has been reported in the literature in a heterozygous individual affected with Parkinson disease, early onset (example: Chen_2022). This report does not provide unequivocal conclusions about association of the variant with Niemann-Pick Disease Type C. 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: 35861376). One submitter has cited clinical-significance assessments 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 uncertain significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.86
BayesDel_addAF	Pathogenic	0.37	D
BayesDel_noAF	Pathogenic	0.46
Cadd	Pathogenic	29
Dann	Uncertain	1.0
DEOGEN2	Pathogenic	0.94	D
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	0.98
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.95	D
M_CAP	Pathogenic	0.49	D
MetaRNN	Pathogenic	0.98	D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	3.7	H
MutationTaster	Benign	1.0	D;D
PrimateAI	Uncertain	0.72	T
PROVEAN	Uncertain	-2.8	D
REVEL	Pathogenic	0.93
Sift	Uncertain	0.0050	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.90
MutPred		0.88		Gain of sheet (P = 0.0827);
MVP		0.94
MPC		0.91
ClinPred		1.0	D
GERP RS		5.7
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.94
gMVP		0.87

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: rs748862167; hg19: chr18-21114508;