chr18-23534480-C-T

Position:

chr18-23534480-C-T

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PM1PM2PM5PP3_StrongPP5_Very_Strong

The NM_000271.5(NPC1):c.3557G>A(p.Arg1186His) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000167 in 1,613,982 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 12/21 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R1186C) has been classified as Likely pathogenic.

Frequency

Genomes: 𝑓 0.000026 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000016 ( 0 hom. )

Consequence

NPC1
NM_000271.5 missense

Scores

Clinical Significance

Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:8

Conservation

PhyloP100: 7.89

Variant links:

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]

NPC1 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Pathogenic. Variant got 18 ACMG points.

PM1

In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 7 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 chr18-23534480-C-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 2125653.Status of the report is criteria_provided_single_submitter, 1 stars.

PP3

MetaRNN computational evidence supports a deleterious effect, 0.978

PP5

Variant 18-23534480-C-T is Pathogenic according to our data. Variant chr18-23534480-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 189174.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr18-23534480-C-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
NPC1	NM_000271.5 linkuse as main transcript	c.3557G>A	p.Arg1186His	missense_variant	23/25	ENST00000269228.10

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
NPC1	ENST00000269228.10 linkuse as main transcript	c.3557G>A	p.Arg1186His	missense_variant	23/25	1	NM_000271.5	P1	O15118-1

Frequencies

GnomAD3 genomes

AF:

0.0000263

AC:

AN:

152242

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000241

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:

0.0000441

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000239

AC:

AN:

251122

Hom.:

AF XY:

0.0000147

AC XY:

AN XY:

135754

show subpopulations

Gnomad AFR exome

AF:

0.000123

Gnomad AMR exome

AF:

0.0000289

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:

0.0000176

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000157

AC:

AN:

1461622

Hom.:

Cov.:

AF XY:

0.0000124

AC XY:

AN XY:

727120

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.0000224

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:

0.0000180

Gnomad4 OTH exome

AF:

0.0000166

GnomAD4 genome

AF:

0.0000263

AC:

AN:

152360

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

74498

show subpopulations

Gnomad4 AFR

AF:

0.0000240

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:

0.0000441

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.0000865

Hom.:

Bravo

AF:

0.0000264

ESP6500AA

AF:

0.00

AC:

ESP6500EA

AF:

0.000116

AC:

ExAC

AF:

0.0000412

AC:

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:8

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Niemann-Pick disease, type C1

Pathogenic:4

Pathogenic, no assertion criteria provided	clinical testing	Natera, Inc.	Dec 24, 2020	- -
Pathogenic, no assertion criteria provided	clinical testing	Counsyl	Dec 21, 2018	- -
Pathogenic, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Jul 22, 2021	- -
Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Sep 25, 2023	For these reasons, this variant has been classified as Pathogenic. Experimental studies have shown that this missense change affects NPC1 function (PMID: 30923329). 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. ClinVar contains an entry for this variant (Variation ID: 189174). This missense change has been observed in individual(s) with Niemann-Pick disease (PMID: 9211849, 22326530, 26666848, 28105569). This variant is present in population databases (rs200444084, gnomAD 0.008%). This sequence change replaces arginine, which is basic and polar, with histidine, which is basic and polar, at codon 1186 of the NPC1 protein (p.Arg1186His). -

not provided

Pathogenic:3

Pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Feb 24, 2017	The R1186H variant in the NPC1 gene has been reported previously in association with Niemann-Pick disease type C (NPC) when present in the homozygous state or with another disease causing variant (Carstea et al., 1997; Sztolsztener et al., 2010; Jahnova et al., 2014). The R1186H variant is not observed at a significant frequency in large population cohorts (Lek et al., 2016; 1000 Genomes Consortium et al., 2015; Exome Variant Server). The R1186H variant is a conservative amino acid substitution, which is not likely to impact secondary protein structure as these residues share similar properties. However, this substitution occurs at a position that is conserved across species and in silico analysis predicts this variant is probably damaging to the protein structure/function. Missense variants in nearby residues (A1187G, A1187V, E1189G, L1191F) have been reported in the Human Gene Mutation Database in association with NPC (Stenson et al., 2014), supporting the functional importance of this region of the protein. We interpret R1186H as a pathogenic variant. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Mar 30, 2016	- -
Pathogenic, criteria provided, single submitter	clinical testing	Mayo Clinic Laboratories, Mayo Clinic	Jun 02, 2022	PP3, PM2, PM3_very_strong, PM5, PS3, PS4 -

Niemann-Pick disease, type C

Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

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

Sep 21, 2020

Variant summary: NPC1 c.3557G>A (p.Arg1186His) results in a non-conservative amino acid change in 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 2.8e-05 in 252814 control chromosomes. c.3557G>A has been widely reported in the literature in multiple individuals affected with Niemann-Pick Disease Type C and subsequently cited by others (example, Reunert_2016, Carstea_1997, Imrie_2015). These data indicate that the variant is very likely to be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. However, at-least one study reported the identification of this variant in a homozygous affected individual with elevated oxysterol levels that are oxidation products of accumulated cholesterol in NP-C cells (Reunert_2016), and serve as a biomarker for the diagnosis of Niemann Pick type C disease. Four clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. All laboratories classified the variant as pathogenic (n=3)/likely pathogenic. Several submitters cite overlapping evidence utilized in the context of this evaluation. Based on the evidence outlined above, the variant was classified as pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.66

BayesDel_addAF

Pathogenic

0.39

BayesDel_noAF

Pathogenic

0.56

CADD

Pathogenic

DANN

Pathogenic

1.0

DEOGEN2

Pathogenic

0.95

Eigen

Pathogenic

0.74

Eigen_PC

Uncertain

0.60

FATHMM_MKL

Pathogenic

0.98

LIST_S2

Pathogenic

0.99

M_CAP

Pathogenic

0.76

MetaRNN

Pathogenic

0.98

MetaSVM

Pathogenic

1.1

MutationAssessor

Pathogenic

3.6

MutationTaster

Benign

1.0

D;D

PrimateAI

Uncertain

0.50

PROVEAN

Pathogenic

-4.7

REVEL

Pathogenic

0.91

Sift

Pathogenic

0.0

Sift4G

Uncertain

0.0020

Polyphen

1.0

Vest4

0.93

MVP

0.97

MPC

1.0

ClinPred

0.99

GERP RS

5.8

RBP_binding_hub_radar

0.92

RBP_regulation_power_radar

2.6

Varity_R

0.89

gMVP

0.90

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

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over