11-6393985-C-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.1430C>A(p.Pro477Gln) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000186 in 1,614,050 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. P477L) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: 𝑓 0.000013 (0 hom., cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: SMPD1 NM_000543.5 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 7.45

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 hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 1 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 chr11-6393985-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 189075.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.951
• PP5: Variant 11-6393985-C-A is Pathogenic according to our data. Variant chr11-6393985-C-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 1489165.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SMPD1	NM_000543.5	c.1430C>A	p.Pro477Gln	missense_variant	5/6	ENST00000342245.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SMPD1	ENST00000342245.9	c.1430C>A	p.Pro477Gln	missense_variant	5/6	1	NM_000543.5	P3

Frequencies

GnomAD3 genomes AF: 0.0000131 AC: 2 AN: 152162 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000483

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461888 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 727246

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

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 AF: 0.0000131 AC: 2 AN: 152162 Hom.: 0 Cov.: 32 AF XY: 0.0000135 AC XY: 1 AN XY: 74322

Gnomad4 AFR AF: 0.0000483

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

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

Likely pathogenic, criteria provided, single submitter

clinical testing

Invitae

Dec 07, 2021

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. This variant disrupts the p.Pro477 amino acid residue in SMPD1. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 12556236, 12712061, 15221801, 17011332). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. 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. This variant has not been reported in the literature in individuals affected with SMPD1-related conditions. This variant is present in population databases (no rsID available, gnomAD 0.01%). This sequence change replaces proline, which is neutral and non-polar, with glutamine, which is neutral and polar, at codon 477 of the SMPD1 protein (p.Pro477Gln). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.90
BayesDel_addAF	Pathogenic	0.53	D
BayesDel_noAF	Pathogenic	0.53
Cadd	Pathogenic	27
Dann	Uncertain	0.99
Eigen	Uncertain	0.56
Eigen_PC	Uncertain	0.56
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.91	D;D
M_CAP	Pathogenic	0.51	D
MetaRNN	Pathogenic	0.95	D;D
MetaSVM	Uncertain	0.30	D
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Uncertain	0.61	T
PROVEAN	Pathogenic	-5.3	D;D
REVEL	Pathogenic	0.90
Sift	Uncertain	0.0010	D;D
Sift4G	Uncertain	0.0030	D;D
Vest4		0.86
MVP		0.98
MPC		0.77
ClinPred		0.99	D
GERP RS		4.7
Varity_R		0.79
gMVP		0.92

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: rs753508874; hg19: chr11-6415215;