rs120074117

chr11-6394204-G-Achr11-6394204-G-Cchr11-6394204-G-T

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PM1 PM2 PM5 PP3_Strong PP5_Very_Strong

The NM_000543.5(SMPD1):c.1493G>A(p.Arg498His) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000062 in 1,614,126 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 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: 𝑓 0.0000066 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000062 (0 hom.)
• Consequence: SMPD1 NM_000543.5 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:8
• Conservation: PhyloP100: 9.37

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.

• PM1: In a hotspot region, there are 5 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 6 uncertain 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 chr11-6394203-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 198095.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.973
• PP5: Variant 11-6394204-G-A is Pathogenic according to our data. Variant chr11-6394204-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 167712.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr11-6394204-G-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SMPD1	NM_000543.5	c.1493G>A	p.Arg498His	missense_variant	6/6	ENST00000342245.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SMPD1	ENST00000342245.9	c.1493G>A	p.Arg498His	missense_variant	6/6	1	NM_000543.5	P3

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152126 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.000207

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.0000119 AC: 3 AN: 251078 Hom.: 0 AF XY: 0.00000737 AC XY: 1 AN XY: 135702

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.0000653

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000882

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000616 AC: 9 AN: 1461882 Hom.: 0 Cov.: 33 AF XY: 0.00000688 AC XY: 5 AN XY: 727240

Gnomad4 AFR exome AF: 0.0000299

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000696

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152244 Hom.: 0 Cov.: 32 AF XY: 0.0000134 AC XY: 1 AN XY: 74424

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.000207

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Bravo AF: 0.0000113

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:8

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Niemann-Pick disease, type A;C0268243:Niemann-Pick disease, type B Pathogenic:3

Pathogenic, criteria provided, single submitter	clinical testing	Centogene AG - the Rare Disease Company	-	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Fulgent Genetics, Fulgent Genetics	Jan 18, 2022	- -
Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Apr 22, 2023	ClinVar contains an entry for this variant (Variation ID: 167712). This variant is also known as c.1487G>A, p.R496H. This missense change has been observed in individuals with Niemann-Pick disease (PMID: 15221801, 27338287, 31965297, 32292456; Invitae). This variant is present in population databases (rs120074117, gnomAD 0.006%). This sequence change replaces arginine, which is basic and polar, with histidine, which is basic and polar, at codon 498 of the SMPD1 protein (p.Arg498His). 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. For these reasons, this variant has been classified as Pathogenic. 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: 1391960, 1885770, 2023926). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. -

Niemann-Pick disease, type A Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Mar 30, 2023	- -
Likely pathogenic, criteria provided, single submitter	research	Diagnostics Division, CENTRE FOR DNA FINGERPRINTING AND DIAGNOSTICS	Apr 25, 2021	- -

not provided Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Eurofins Ntd Llc (ga)

Jan 08, 2014

- -

Sphingomyelin/cholesterol lipidosis Pathogenic:1

Likely pathogenic, criteria provided, single submitter

curation

Broad Center for Mendelian Genomics, Broad Institute of MIT and Harvard

Jan 22, 2020

The p.Arg498His variant in SMPD1 (also known as p.Arg496His due to a difference in cDNA numbering) has been reported in at least 2 individuals with Niemann-Pick disease (PMID: 27338287, 15221801) and has been identified in 0.007% (2/30614) of South Asian chromosomes and 0.001% (1/113412) of European (non-Finnish) chromosomes by the Genome Aggregation Database (gnomAD, http://gnomad.broadinstitute.org; dbSNP rs120074117). Although this variant has been seen in the general population, its frequency is low enough to be consistent with a recessive carrier frequency. This variant has also been reported in ClinVar (VariationID: 198095) as likely pathogenic by EGL Genetic Diagnostics. Computational prediction tools and conservation analyses suggest that this variant may impact the protein, though this information is not predictive enough to determine pathogenicity. The presence of this variant in an affected homozygote and in combination with a reported pathogenic variant in an individual with Niemann-Pick disease increases the likelihood that the p.Arg498His variant is pathogenic (VariationID: 167710; PMID: 27338287, 15221801). The phenotype of an individual compound heterozygous for this variant is highly specific for Niemann-Pick disease based on acid sphingomyelinase activity being <10% of normal, consistent with disease (PMID: 27338287). Multiple variants in the same region as p.Arg498His have been reported in association with disease in ClinVar and the literature and the variant is located in a region of SMPD1 that is essential to protein folding and stability, suggesting that this variant is in a hot spot and functional domain and supports pathogenicity (VariationID: 2980, 198095; PMID: 18815062, 27725636; DOI: 10.1111/febs.13655). Two additional pathogenic and likely pathogenic variants, resulting in a different amino acid change at the same position, p.Arg498Leu and p.Arg498Cys have been reported in association with disease in the literature and ClinVar, supporting that a change at this position may not be tolerated (VariationID: 2980, 198095; PMID: 29995201, 18815062, 15221801, 27338287, 25834946, 23356216). In summary, although additional studies are required to fully establish its clinical significance, this variant is likely pathogenic. ACMG/AMP Criteria applied: PM2, PM5, PM1, PM3, PP3, PP4 (Richards 2015). -

Abnormality of metabolism/homeostasis Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Kariminejad - Najmabadi Pathology & Genetics Center

Jul 10, 2021

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.76
BayesDel_addAF	Pathogenic	0.46	D
BayesDel_noAF	Pathogenic	0.60
Cadd	Pathogenic	31
Dann	Pathogenic	1.0
Eigen	Uncertain	0.48
Eigen_PC	Uncertain	0.46
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.94	D;D
M_CAP	Pathogenic	0.34	D
MetaRNN	Pathogenic	0.97	D;D
MetaSVM	Uncertain	0.18	D
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Uncertain	0.64	T
PROVEAN	Pathogenic	-4.6	D;D
REVEL	Pathogenic	0.96
Sift	Pathogenic	0.0	D;D
Sift4G	Uncertain	0.0020	D;D
Vest4		0.97
MVP		1.0
MPC		0.89
ClinPred		1.0	D
GERP RS		4.7
Varity_R		0.82
gMVP		0.94

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.12		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: rs120074117; hg19: chr11-6415434;