11-6390633-GC-G

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_000543.5(SMPD1):c.39del(p.Arg14GlyfsTer63) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Likely pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. C12C) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 32)
• Consequence: SMPD1 NM_000543.5 frameshift
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: -1.25

Genes affected

SMPD1 (HGNC:11120): (sphingomyelin phosphodiesterase 1) The protein encoded by this gene is a lysosomal acid sphingomyelinase that converts sphingomyelin to ceramide. The encoded protein also has phospholipase C activity. Defects in this gene are a cause of Niemann-Pick disease type A (NPA) and Niemann-Pick disease type B (NPB). Multiple transcript variants encoding different isoforms have been identified. [provided by RefSeq, Jul 2010]

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant located near the start codon (<100nt), not predicted to undergo nonsense mediated mRNA decay. There are 400 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 11-6390633-GC-G is Pathogenic according to our data. Variant chr11-6390633-GC-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 1460100.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SMPD1	NM_000543.5	c.39del	p.Arg14GlyfsTer63	frameshift_variant	1/6	ENST00000342245.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SMPD1	ENST00000342245.9	c.39del	p.Arg14GlyfsTer63	frameshift_variant	1/6	1	NM_000543.5	P3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Niemann-Pick disease, type A;C0268243:Niemann-Pick disease, type B Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Invitae

Aug 13, 2021

This sequence change creates a premature translational stop signal (p.Arg14Glyfs*63) in the SMPD1 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in SMPD1 are known to be pathogenic (PMID: 12369017, 15221801). This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals affected with SMPD1-related conditions. For these reasons, this variant has been classified as Pathogenic. -

Niemann-Pick disease, type A Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Baylor Genetics

Apr 11, 2022

- -

Computational scores

Source: dbNSFP v4.3

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

No publications associated with this variant yet.

Other links and lift over

hg19: chr11-6411863;