18-23539433-C-T

Position:

chr18-23539433-C-T

Variant summary

Our verdict is Likely pathogenic. Variant got 9 ACMG points: 9P and 0B. PM1PM2PP3_StrongPP5

The NM_000271.5(NPC1):c.2833G>A(p.Asp945Asn) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000248 in 1,613,568 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).

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 33)

Exomes 𝑓: 0.0000021 ( 0 hom. )

Consequence

NPC1
NM_000271.5 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1U:2

Conservation

PhyloP100: 7.75

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:

NPC1 (HGNC:):

NPC1 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Likely_pathogenic. Variant got 9 ACMG points.

PM1

In a helix (size 7) in uniprot entity NPC1_HUMAN there are 10 pathogenic changes around while only 0 benign (100%) in NM_000271.5

PM2

Very rare variant in population databases, with high coverage;

PP3

MetaRNN computational evidence supports a deleterious effect, 0.994

PP5

Variant 18-23539433-C-T is Pathogenic according to our data. Variant chr18-23539433-C-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 539312.We mark this variant Likely_pathogenic, oryginal submissions are: {Uncertain_significance=1, Likely_pathogenic=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
NPC1	NM_000271.5 linkuse as main transcript	c.2833G>A	p.Asp945Asn	missense_variant	19/25	ENST00000269228.10	NP_000262.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	UniProt
NPC1	ENST00000269228.10 linkuse as main transcript	c.2833G>A	p.Asp945Asn	missense_variant	19/25	1	NM_000271.5	ENSP00000269228.4	O15118-1
NPC1	ENST00000591051.1 linkuse as main transcript	c.1909G>A	p.Asp637Asn	missense_variant	12/18	2		ENSP00000467636.1	K7EQ23
NPC1	ENST00000591075.1 linkuse as main transcript	n.466G>A		non_coding_transcript_exon_variant	1/3	4

Frequencies

GnomAD3 genomes

AF:

0.00000657

AC:

AN:

152204

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

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:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.00000798

AC:

AN:

250474

Hom.:

AF XY:

0.00000739

AC XY:

AN XY:

135286

show subpopulations

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 SAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.0000463

Gnomad NFE exome

AF:

0.00000882

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000205

AC:

AN:

1461364

Hom.:

Cov.:

AF XY:

0.00000275

AC XY:

AN XY:

726906

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.00

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.00000270

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

AF:

0.00000657

AC:

AN:

152204

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

74366

show subpopulations

Gnomad4 AFR

AF:

0.00

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:

0.0000147

Gnomad4 OTH

AF:

0.00

Bravo

AF:

0.00000378

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1Uncertain:2

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

Niemann-Pick disease, type C1

Uncertain:2

Uncertain significance, no assertion criteria provided	clinical testing	Natera, Inc.	Sep 16, 2020	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Mar 26, 2022	This sequence change replaces aspartic acid, which is acidic and polar, with asparagine, which is neutral and polar, at codon 945 of the NPC1 protein (p.Asp945Asn). The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This missense change has been observed in individual(s) with Niemann-Pick disease type C for which no second variant in NPC1 was found (PMID: 12955717, 19744920). ClinVar contains an entry for this variant (Variation ID: 539312). 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. 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. -

Niemann-Pick disease, type C

Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

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

Dec 02, 2022

Variant summary: NPC1 c.2833G>A (p.Asp945Asn) 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 8e-06 in 250474 control chromosomes (gnomAD). c.2833G>A has been reported in the literature in individuals affected with Niemann-Pick Disease Type C and was reported to cause 'severe' biochemical phenotype (Park_2003, Garver_2010, Ribas_2016, Lopez de Frutos_2021). These data indicate that the variant is likely to be associated with disease. Experimental evidence evaluating an impact on protein function, demonstrated the variant to cause a reduction in total protein expression and result in protein of distinct molecular weights, one equivalent to the wild type and the other equivalent to that found in lower-molecular-weight mutants. Furthermore, the variant showed defective cholesterol trafficking. Taken together, the authors concluded the variant to be pathogenic (Erwood_2019). Two ClinVar submitters (evaluation after 2014) cite the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as likely pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.89

BayesDel_addAF

Pathogenic

0.19

BayesDel_noAF

Uncertain

0.040

CADD

Pathogenic

DANN

Pathogenic

1.0

DEOGEN2

Pathogenic

0.87

Eigen

Pathogenic

0.95

Eigen_PC

Pathogenic

0.84

FATHMM_MKL

Uncertain

0.97

LIST_S2

Uncertain

0.96

M_CAP

Pathogenic

0.50

MetaRNN

Pathogenic

0.99

MetaSVM

Pathogenic

1.1

MutationAssessor

Pathogenic

3.7

PrimateAI

Uncertain

0.75

PROVEAN

Pathogenic

-4.9

REVEL

Pathogenic

0.79

Sift

Pathogenic

0.0

Sift4G

Uncertain

0.0070

Polyphen

1.0

Vest4

0.98

MutPred

0.95

Gain of relative solvent accessibility (P = 0.1259);

MVP

0.98

MPC

0.90

ClinPred

1.0

GERP RS

5.3

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.1

Varity_R

0.85

gMVP

0.96

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