18-23536862-T-C

Position:

• chr18-23536862-T-C

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.3056A>G​(p.Tyr1019Cys) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000041 in 1,461,684 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 (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000041 (0 hom.)
• Consequence: NPC1 NM_000271.5 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: 8.01

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 (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 16 ACMG points.

• PM1: In a turn (size 5) in uniprot entity NPC1_HUMAN there are 4 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, 0.995
• PP5: Variant 18-23536862-T-C is Pathogenic according to our data. Variant chr18-23536862-T-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 371419.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr18-23536862-T-C is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
NPC1	NM_000271.5	c.3056A>G	p.Tyr1019Cys	missense_variant	21/25	ENST00000269228.10	NP_000262.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
NPC1	ENST00000269228.10	c.3056A>G	p.Tyr1019Cys	missense_variant	21/25	1	NM_000271.5	ENSP00000269228.4
NPC1	ENST00000591051.1	c.2132A>G	p.Tyr711Cys	missense_variant	14/18	2		ENSP00000467636.1
NPC1	ENST00000591075.1	n.689A>G		non_coding_transcript_exon_variant	3/3	4
NPC1	ENST00000591955.1	n.399A>G		non_coding_transcript_exon_variant	2/2	4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000796 AC: 2 AN: 251300 Hom.: 0 AF XY: 0.0000147 AC XY: 2 AN XY: 135834

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: 0.0000176

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000410 AC: 6 AN: 1461684 Hom.: 0 Cov.: 32 AF XY: 0.00000550 AC XY: 4 AN XY: 727144

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: 0.00000540

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ExAC AF: 0.00000824 AC: 1

EpiCase AF: 0.00

EpiControl AF: 0.0000593

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Niemann-Pick disease, type C1 Pathogenic:4

Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Jul 14, 2023	This sequence change replaces tyrosine, which is neutral and polar, with cysteine, which is neutral and slightly polar, at codon 1019 of the NPC1 protein (p.Tyr1019Cys). This variant is present in population databases (rs781261962, gnomAD 0.002%). This missense change has been observed in individual(s) with Niemann-Pick type C (PMID: 32138288). ClinVar contains an entry for this variant (Variation ID: 371419). 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. Studies have shown that this missense change alters NPC1 gene expression (PMID: 23430855). For these reasons, this variant has been classified as Pathogenic. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Fulgent Genetics, Fulgent Genetics	Feb 15, 2022	- -
Pathogenic, criteria provided, single submitter	clinical testing	Foundation for Research in Genetics and Endocrinology, FRIGE's Institute of Human Genetics	Apr 12, 2022	A Homozygous missense variation in exon 21 of the NPC1 gene that results in the amino acid substitution of Cystine for Tyrosine at codon 1019 was detected. The observed variant c.3056A>G (p.Tyr1019Cys) has not been reported in the 1000 genomes and has a MAF of 000796% in the gnomAD database. The in silico prediction of the variant is damaging by PolyPhen-2 (HumDiv), LRT and MutationTaster2. In summary, the variant meets our criteria to be classified as pathogenic. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Counsyl	Sep 22, 2016	- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.95
BayesDel_addAF	Pathogenic	0.55	D
BayesDel_noAF	Pathogenic	0.57
CADD	Pathogenic	26
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.91	D
Eigen	Pathogenic	0.69
Eigen_PC	Uncertain	0.51
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Uncertain	0.97	D
M_CAP	Pathogenic	0.67	D
MetaRNN	Pathogenic	1.0	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.9	H
PrimateAI	Pathogenic	0.81	D
PROVEAN	Pathogenic	-8.4	D
REVEL	Pathogenic	0.94
Sift	Uncertain	0.0010	D
Sift4G	Uncertain	0.0030	D
Polyphen		1.0	D
Vest4		0.99
MutPred		0.95		Loss of phosphorylation at Y1019 (P = 0.0953);
MVP		0.96
MPC		1.0
ClinPred		1.0	D
GERP RS		5.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.86
gMVP		0.97

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.020		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: rs781261962; hg19: chr18-21116826;