11-6392141-C-A

Position:

• chr11-6392141-C-A

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM2 PP3_Strong PP5_Moderate

The NM_000543.5(SMPD1):​c.1076C>A​(p.Ala359Asp) variant causes a missense change. The variant allele was found at a frequency of 0.00000205 in 1,461,878 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★).

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: SMPD1 NM_000543.5 missense
• Clinical Significance: Pathogenic criteria provided, single submitter P:1 O:1
• Conservation: PhyloP100: 5.69

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]

SMPD1 (HGNC:):

ACMG classification

Verdict is Likely_pathogenic. Variant got 8 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.957
• PP5: Variant 11-6392141-C-A is Pathogenic according to our data. Variant chr11-6392141-C-A is described in ClinVar as [Pathogenic]. Clinvar id is 203427.Status of the report is criteria_provided_single_submitter, 1 stars. Variant chr11-6392141-C-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
SMPD1	NM_000543.5	c.1076C>A	p.Ala359Asp	missense_variant	2/6	ENST00000342245.9	NP_000534.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
SMPD1	ENST00000342245.9	c.1076C>A	p.Ala359Asp	missense_variant	2/6	1	NM_000543.5	ENSP00000340409.4

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1461878 Hom.: 0 Cov.: 36 AF XY: 0.00000275 AC XY: 2 AN XY: 727238

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000447

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: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 31

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1 Other:1

Revision: criteria provided, single submitter

Submissions by phenotype

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

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

May 13, 2022

This missense change has been observed in individuals with Niemann-Pick disease (PMID: 25920558). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces alanine, which is neutral and non-polar, with aspartic acid, which is acidic and polar, at codon 359 of the SMPD1 protein (p.Ala359Asp). This variant is also known as Ala357Asp. ClinVar contains an entry for this variant (Variation ID: 203427). 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 SMPD1 protein function. Experimental studies have shown that this missense change affects SMPD1 function (PMID: 25920558, 27659707). For these reasons, this variant has been classified as Pathogenic. -

Sphingomyelin/cholesterol lipidosis Other:1

not provided, no classification provided

literature only

GeneReviews

-

In Chile, screening of 1,691 healthy persons for this common SMPD1 pathogenic variant found a heterozygote frequency of 1:105.7, predicting a disease incidence of 1:44,960 -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.64
BayesDel_addAF	Pathogenic	0.45	D
BayesDel_noAF	Pathogenic	0.40
CADD	Uncertain	25
DANN	Uncertain	1.0
Eigen	Uncertain	0.39
Eigen_PC	Uncertain	0.45
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Benign	0.86	D;D
M_CAP	Uncertain	0.28	D
MetaRNN	Pathogenic	0.96	D;D
MetaSVM	Benign	-0.42	T
PrimateAI	Uncertain	0.60	T
PROVEAN	Uncertain	-3.8	D;D
REVEL	Pathogenic	0.91
Sift	Uncertain	0.0050	D;D
Sift4G	Uncertain	0.015	D;D
Vest4		0.96
MVP		0.97
MPC		0.99
ClinPred		0.98	D
GERP RS		5.0
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.90
gMVP		0.99

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: rs797044800; hg19: chr11-6413371;