rs786204714

chr18-23539465-C-Achr18-23539465-C-T

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM1 PM2 PM5 PP3_Moderate

The NM_000271.5(NPC1):c.2801G>T(p.Arg934Leu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R934Q) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 33)
• Consequence: NPC1 NM_000271.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 2.59

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 Likely_pathogenic. Variant got 8 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
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr18-23539465-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 189117.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.849

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
NPC1	NM_000271.5	c.2801G>T	p.Arg934Leu	missense_variant	19/25	ENST00000269228.10

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
NPC1	ENST00000269228.10	c.2801G>T	p.Arg934Leu	missense_variant	19/25	1	NM_000271.5	P1
NPC1	ENST00000591051.1	c.1880G>T	p.Arg627Leu	missense_variant	12/18	2
NPC1	ENST00000591075.1	n.434G>T		non_coding_transcript_exon_variant	1/3	4

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Eurofins Ntd Llc (ga)

Jul 05, 2016

- -

Niemann-Pick disease, type C1 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 12, 2018

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.22
BayesDel_addAF	Pathogenic	0.30	D
BayesDel_noAF	Pathogenic	0.20
Cadd	Uncertain	23
Dann	Uncertain	1.0
DEOGEN2	Benign	0.37	T
Eigen	Benign	0.041
Eigen_PC	Benign	0.16
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.92	D
M_CAP	Uncertain	0.18	D
MetaRNN	Pathogenic	0.85	D
MetaSVM	Uncertain	0.40	D
MutationAssessor	Uncertain	2.4	M
MutationTaster	Benign	1.0	D;D
PrimateAI	Uncertain	0.49	T
PROVEAN	Benign	-2.1	N
REVEL	Uncertain	0.57
Sift	Benign	0.16	T
Sift4G	Benign	0.17	T
Polyphen		0.044	B
Vest4		0.77
MutPred		0.71		Loss of solvent accessibility (P = 0.0606);
MVP		0.88
MPC		0.35
ClinPred		0.85	D
GERP RS		5.5
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.60
gMVP		0.82

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.18		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: rs786204714; hg19: chr18-21119429;