11-6390626-C-T

Position:

• chr11-6390626-C-T

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.28C>T​(p.Gln10Ter) variant causes a stop gained 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 Likely pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. Q10Q) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 32)
• Consequence: SMPD1 NM_000543.5 stop_gained
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: 0.122

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 404 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 11-6390626-C-T is Pathogenic according to our data. Variant chr11-6390626-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 550117.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.28C>T	p.Gln10Ter	stop_gained	1/6	ENST00000342245.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SMPD1	ENST00000342245.9	c.28C>T	p.Gln10Ter	stop_gained	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:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Niemann-Pick disease, type A Pathogenic:2

Likely pathogenic, criteria provided, single submitter	clinical testing	Counsyl	Dec 29, 2016	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Jan 03, 2024	- -

SMPD1-related disorder Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

PreventionGenetics, part of Exact Sciences

Nov 02, 2023

The SMPD1 c.28C>T variant is predicted to result in premature protein termination (p.Gln10*). This variant was reported in an individual with Niemann-Pick disease (Vélez Pinos et al. 2023. PubMed ID: 36779112). This variant has not been reported in a large population database (http://gnomad.broadinstitute.org), indicating this variant is rare. Nonsense variants in SMPD1 are expected to be pathogenic. This variant is interpreted as likely pathogenic. -

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

Pathogenic, criteria provided, single submitter

clinical testing

Invitae

Aug 04, 2023

For these reasons, this variant has been classified as Pathogenic. ClinVar contains an entry for this variant (Variation ID: 550117). This variant has not been reported in the literature in individuals affected with SMPD1-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change creates a premature translational stop signal (p.Gln10*) 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). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.62	D
BayesDel_noAF	Uncertain	0.040
CADD	Pathogenic	33
DANN	Uncertain	1.0
Eigen	Uncertain	0.28
Eigen_PC	Benign	-0.070
FATHMM_MKL	Benign	0.16	N
MutationTaster	Benign	1.0	A;A;A;A
Vest4		0.64
GERP RS		3.0
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.0

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

LitVar

Other links and lift over

dbSNP: rs1205990349; hg19: chr11-6411856;