rs797044431

Positions:

• chr18-23536877-CT-C

Variant summary

Our verdict is Likely pathogenic. Variant got 7 ACMG points: 7P and 0B. PVS1_Moderate PM2 PP3 PP5_Moderate

The NM_000271.5(NPC1):​c.3042-2delA variant causes a splice acceptor, intron change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 1/1 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: NPC1 NM_000271.5 splice_acceptor, intron
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:2
• 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 Likely_pathogenic. Variant got 7 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.052905917 fraction of the gene. Cryptic splice site detected, with MaxEntScore 4.8, offset of -13, new splice context is: tggactctcttgacacccAGgat. Cryptic site results in frameshift change. If cryptic site found is not functional and variant results in exon loss, it results in inframe change.
• PM2: Very rare variant in population databases, with high coverage
• PP3: Multiple lines of computational evidence support a deleterious effect 2: max_spliceai, phyloP100way_vertebrate [when was below the threshold]
• PP5: Variant 18-23536877-CT-C is Pathogenic according to our data. Variant chr18-23536877-CT-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 2963.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
NPC1	NM_000271.5	c.3042-2delA		splice_acceptor_variant, intron_variant		ENST00000269228.10	NP_000262.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
NPC1	ENST00000269228.10	c.3042-2delA		splice_acceptor_variant, intron_variant		1	NM_000271.5	ENSP00000269228.4
NPC1	ENST00000591051.1	c.2118-2delA		splice_acceptor_variant, intron_variant		2		ENSP00000467636.1
NPC1	ENST00000591075.1	n.675-2delA		splice_acceptor_variant, intron_variant		4
NPC1	ENST00000591955.1	n.385-2delA		splice_acceptor_variant, intron_variant		4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, single submitter

Submissions by phenotype

Niemann-Pick disease, type C1, adult form Pathogenic:1

Pathogenic, no assertion criteria provided

literature only

OMIM

Jul 01, 1999

- -

Niemann-Pick disease, type C1 Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Counsyl

Apr 17, 2018

- -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.99		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.44		Position offset: 13
DS_AL_spliceai		0.99		Position offset: -1

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs797044431; hg19: chr18-21116841;