rs756815030

Variant names:

• chr18-23538609-CCT-C
• rs756815030
• NM_000271.5:c.2972_2973delAG

Variant summary

Our verdict is Pathogenic. The variant received 15 ACMG points: 15P and 0B. PVS1 PS3 PM2 PP5

The NM_000271.5(NPC1):​c.2972_2973delAG​(p.Gln991ArgfsTer15) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000273 in 1,614,068 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). ClinVar reports functional evidence for this variant: "SCV000915796: Data from Tarugi et al. (2002) suggest the allele carrying p.Gln991ArgfsTer15 is not transcribed or mRNA is rapidly degraded making it non-functional, as the allele was not identified using reverse transcription of RNA in fibroblasts of two unrelated compound heterozygous patients. Tarugi et al. (2002)" and additional evidence is available in ClinVar. Synonymous variant affecting the same amino acid position (i.e. Q991Q) has been classified as Likely benign. Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000029 (0 hom.)
• Consequence: NPC1 NM_000271.5 frameshift
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:10 U:1
• Conservation: PhyloP100: 1.47
• Publications: 13 publications found

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 Gene-Disease associations (from GenCC):

• Niemann-Pick disease, type C1

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: ClinGen, Genomics England PanelApp, Labcorp Genetics (formerly Invitae), Myriad Women’s Health, Laboratory for Molecular Medicine, G2P
• Niemann-Pick disease type C, adult neurologic onset

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• Niemann-Pick disease type C, juvenile neurologic onset

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• Niemann-Pick disease type C, late infantile neurologic onset

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• Niemann-Pick disease type C, severe early infantile neurologic onset

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• Niemann-Pick disease type C, severe perinatal form

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 15 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PS3: PS3 evidence extracted from ClinVar submissions: SCV000915796: Data from Tarugi et al. (2002) suggest the allele carrying p.Gln991ArgfsTer15 is not transcribed or mRNA is rapidly degraded making it non-functional, as the allele was not identified using reverse transcription of RNA in fibroblasts of two unrelated compound heterozygous patients. Tarugi et al. (2002); SCV001653013: In vitro functional studies provide some evidence that this variant does impacts protein function (Tarugi 2002 PMID: 12401890)
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 18-23538609-CCT-C is Pathogenic according to our data. Variant chr18-23538609-CCT-C is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 188932.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000271.5. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	NPC1	NM_000271.5	MANE Select	c.2972_2973delAG	p.Gln991ArgfsTer15	frameshift	Exon 20 of 25	NP_000262.2	O15118-1

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	NPC1	ENST00000269228.10	TSL:1 MANE Select	c.2972_2973delAG	p.Gln991ArgfsTer15	frameshift	Exon 20 of 25	ENSP00000269228.4	O15118-1
	NPC1	ENST00000897526.1		c.3023_3024delAG	p.Gln1008ArgfsTer15	frameshift	Exon 20 of 25	ENSP00000567585.1
	NPC1	ENST00000926494.1		c.2972_2973delAG	p.Gln991ArgfsTer15	frameshift	Exon 20 of 25	ENSP00000596553.1

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152200 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.000288

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.0000477 AC: 12 AN: 251484 AF XY: 0.0000294

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000289

Gnomad ASJ exome AF: 0.0000992

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.0000924

Gnomad NFE exome AF: 0.0000527

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000294 AC: 43 AN: 1461868 Hom.: 0 AF XY: 0.0000248 AC XY: 18 AN XY: 727230

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.0000224 AC: 1 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.000191 AC: 5 AN: 26136

East Asian (EAS) AF: 0.0000252 AC: 1 AN: 39698

South Asian (SAS) AF: 0.0000464 AC: 4 AN: 86258

European-Finnish (FIN) AF: 0.0000749 AC: 4 AN: 53414

Middle Eastern (MID) AF: 0.000173 AC: 1 AN: 5768

European-Non Finnish (NFE) AF: 0.0000207 AC: 23 AN: 1111994

Other (OTH) AF: 0.0000662 AC: 4 AN: 60396

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152200 Hom.: 0 Cov.: 32 AF XY: 0.0000134 AC XY: 1 AN XY: 74372

African (AFR) AF: 0.00 AC: 0 AN: 41454

American (AMR) AF: 0.00 AC: 0 AN: 15280

Ashkenazi Jewish (ASJ) AF: 0.000288 AC: 1 AN: 3468

East Asian (EAS) AF: 0.00 AC: 0 AN: 5200

South Asian (SAS) AF: 0.00 AC: 0 AN: 4832

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10612

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 68032

Other (OTH) AF: 0.00 AC: 0 AN: 2094

Alfa AF: 0.0000712 Hom.: 0

Bravo AF: 0.0000227

EpiCase AF: 0.0000545

EpiControl AF: 0.0000593

ClinVar

ClinVar submissions

Significance: Conflicting classifications of pathogenicity

Revision: criteria provided, conflicting classifications

Pathogenic	VUS	Benign	Condition
5	-	-	Niemann-Pick disease, type C1 (5)
2	1	-	not provided (3)
2	-	-	Niemann-Pick disease, type C (2)
1	-	-	NPC1-related disorder (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		1.5
Mutation Taster		=0/200	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.14		Details are displayed if max score is > 0.2

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

Other links and lift over

dbSNP: rs756815030; hg19: chr18-21118573;