18-23536814-G-A

Position:

• chr18-23536814-G-A

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PM1 PM2 PP3_Strong PP5_Very_Strong

The NM_000271.5(NPC1):​c.3104C>T​(p.Ala1035Val) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000342 in 1,461,872 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 Likely pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. A1035A) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000034 (0 hom.)
• Consequence: NPC1 NM_000271.5 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:6
• Conservation: PhyloP100: 10.0

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 16 ACMG points.

• PM1: In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 3 uncertain in NM_000271.5
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.987
• PP5: Variant 18-23536814-G-A is Pathogenic according to our data. Variant chr18-23536814-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 2972.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr18-23536814-G-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
NPC1	NM_000271.5	c.3104C>T	p.Ala1035Val	missense_variant	21/25	ENST00000269228.10

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
NPC1	ENST00000269228.10	c.3104C>T	p.Ala1035Val	missense_variant	21/25	1	NM_000271.5	P1
NPC1	ENST00000591051.1	c.2183C>T	p.Ala728Val	missense_variant	14/18	2
NPC1	ENST00000591075.1	n.737C>T		non_coding_transcript_exon_variant	3/3	4
NPC1	ENST00000591955.1	n.447C>T		non_coding_transcript_exon_variant	2/2	4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000795 AC: 2 AN: 251452 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135910

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: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.000326

GnomAD4 exome AF: 0.00000342 AC: 5 AN: 1461872 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 727234

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000224

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: 0.00000360

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

Alfa AF: 0.0000425 Hom.: 0

Bravo AF: 0.0000151

ExAC AF: 0.00000824 AC: 1

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:6

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Niemann-Pick disease, type C1 Pathogenic:5

Pathogenic, no assertion criteria provided	literature only	OMIM	Jul 01, 2001	- -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Nov 09, 2023	This sequence change replaces alanine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 1035 of the NPC1 protein (p.Ala1035Val). This variant is present in population databases (rs28942107, gnomAD 0.003%). This missense change has been observed in individual(s) with Niemann-Pick disease type C (PMID: 11479732, 16098014, 23183285; Invitae). ClinVar contains an entry for this variant (Variation ID: 2972). 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%. For these reasons, this variant has been classified as Pathogenic. -
Pathogenic, no assertion criteria provided	clinical testing	Natera, Inc.	May 06, 2021	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Counsyl	Sep 28, 2016	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Fulgent Genetics, Fulgent Genetics	Feb 26, 2022	- -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Eurofins Ntd Llc (ga)

Jul 02, 2012

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.68
BayesDel_addAF	Pathogenic	0.48	D
BayesDel_noAF	Pathogenic	0.53
CADD	Pathogenic	27
DANN	Pathogenic	1.0
DEOGEN2	Uncertain	0.80	D
Eigen	Pathogenic	0.89
Eigen_PC	Pathogenic	0.83
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Pathogenic	0.98	D
M_CAP	Pathogenic	0.63	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	3.5	H
MutationTaster	Benign	1.0	A;A
PrimateAI	Uncertain	0.63	T
PROVEAN	Uncertain	-3.6	D
REVEL	Pathogenic	0.92
Sift	Uncertain	0.0020	D
Sift4G	Benign	0.067	T
Polyphen		1.0	D
Vest4		0.96
MutPred		0.87		Gain of sheet (P = 0.039);
MVP		0.96
MPC		0.91
ClinPred		0.97	D
GERP RS		5.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.74
gMVP		0.97

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: rs28942107; hg19: chr18-21116778;