rs1057516949

Variant names:

• chr11-6390746-TCTGA-T
• rs1057516949
• NM_000543.5:c.151_154delGACT

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.151_154delGACT​(p.Asp51LeufsTer25) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000749 in 1,601,852 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Likely pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: 𝑓 0.0000067 (0 hom., cov: 33)
  • Exomes 𝑓: 0.0000076 (0 hom.)
• Consequence: SMPD1 NM_000543.5 frameshift
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: 1.84

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 undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 11-6390746-TCTGA-T is Pathogenic according to our data. Variant chr11-6390746-TCTGA-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 371029.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SMPD1	NM_000543.5	c.151_154delGACT	p.Asp51LeufsTer25	frameshift_variant	Exon 1 of 6	ENST00000342245.9	NP_000534.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SMPD1	ENST00000342245.9	c.151_154delGACT	p.Asp51LeufsTer25	frameshift_variant	Exon 1 of 6	1	NM_000543.5	ENSP00000340409.4

Frequencies

GnomAD3 genomes AF: 0.00000665 AC: 1 AN: 150292 Hom.: 0 Cov.: 33

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: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000149

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.00000805 AC: 2 AN: 248452 Hom.: 0 AF XY: 0.0000149 AC XY: 2 AN XY: 134532

Gnomad AFR exome AF: 0.0000629

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000891

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000758 AC: 11 AN: 1451560 Hom.: 0 AF XY: 0.0000125 AC XY: 9 AN XY: 722342

Gnomad4 AFR exome AF: 0.0000300

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: 0.00000906

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.00000665 AC: 1 AN: 150292 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 73338

Gnomad4 AFR AF: 0.00

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: 0.0000149

Gnomad4 OTH AF: 0.00

Bravo AF: 0.00000378

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:3

Sep 07, 2023

Baylor Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Jan 22, 2020

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

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: curation

The p.Asp51LeufsTer25 variant in SMPD1 (also known as p.Asp49LeufsTer25 due to a difference in cDNA numbering) has been reported in one Cambodian individual with Niemann-Pick disease (PMID: 24718843) and has been identified in 0.006% (1/15898) of African chromosomes and 0.001% (1/112280) of European (non-Finnish) chromosomes by the Genome Aggregation Database (gnomAD, http://gnomad.broadinstitute.org; dbSNP rs1057516949). 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: 371029) as likely pathogenic by Counsyl. This variant is predicted to cause a frameshift, which alters the protein's amino acid sequence beginning at position 51 and leads to a premature termination codon 25 amino acids downstream. This alteration is then predicted to lead to a truncated or absent protein. Loss of function of the SMPD1 gene is an established disease mechanism in autosomal recessive Niemann-Pick disease. 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: 24718843). In summary, this variant meets criteria to be classified as pathogenic for Niemann-Pick disease in an autosomal recessive manner based on the prediction that it will cause loss of function, the phenotype of an individual with the variant being highly specific for disease, and the low frequency of the variant in the general population. ACMG/AMP Criteria applied: PVS1, PM2, PP4 (Richards 2015). -

Jun 08, 2016

Counsyl

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

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

Feb 01, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change creates a premature translational stop signal (p.Asp51Leufs*25) 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). This variant is present in population databases (no rsID available, gnomAD 0.007%). This premature translational stop signal has been observed in individual(s) with acid sphingomyelinase-deficient Niemann-Pick disease (PMID: 24718843). ClinVar contains an entry for this variant (Variation ID: 371029). For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

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: rs1057516949; hg19: chr11-6411976;