chr11-6394203-C-A

Variant names:

• chr11-6394203-C-A
• NM_000543.5:c.1492C>A

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PM1 PM2 PM5 PP3_Strong PP5_Moderate

The NM_000543.5(SMPD1):​c.1492C>A​(p.Arg498Ser) variant causes a missense change. 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 (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R498C) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: SMPD1 NM_000543.5 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 5.60

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 12 ACMG points.

• PM1: In a strand (size 7) in uniprot entity ASM_HUMAN there are 5 pathogenic changes around while only 0 benign (100%) in NM_000543.5
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chrnull-null-null-null is described in UniProt as null.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.987
• PP5: Variant 11-6394203-C-A is Pathogenic according to our data. Variant chr11-6394203-C-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 2952393.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SMPD1	NM_000543.5	c.1492C>A	p.Arg498Ser	missense_variant	Exon 6 of 6	ENST00000342245.9	NP_000534.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SMPD1	ENST00000342245.9	c.1492C>A	p.Arg498Ser	missense_variant	Exon 6 of 6	1	NM_000543.5	ENSP00000340409.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

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

Feb 19, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces arginine, which is basic and polar, with serine, which is neutral and polar, at codon 498 of the SMPD1 protein (p.Arg498Ser). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with SMPD1-related conditions. 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 with a positive predictive value of 95%. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may create or strengthen a splice site. This variant disrupts the p.Arg498 amino acid residue in SMPD1. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 15221801, 27338287, 31965297, 32292456; Invitae). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.56	D
BayesDel_noAF	Pathogenic	0.57
CADD	Pathogenic	33
DANN	Uncertain	1.0
Eigen	Uncertain	0.62
Eigen_PC	Uncertain	0.48
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Benign	0.85	D;D
M_CAP	Pathogenic	0.85	D
MetaRNN	Pathogenic	0.99	D;D
MetaSVM	Pathogenic	1.1	D
PrimateAI	Uncertain	0.62	T
PROVEAN	Pathogenic	-5.5	D;D
REVEL	Pathogenic	0.92
Sift	Pathogenic	0.0	D;D
Sift4G	Uncertain	0.0020	D;D
Vest4		0.97
MVP		0.99
MPC		0.81
ClinPred		1.0	D
GERP RS		3.8
Varity_R		0.95
gMVP		0.97

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.47		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.47		Position offset: 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: chr11-6415433;