Genetic Variant SMPD1:p.Tyr4PhefsTer51 (chr11-6390605-C-CGCTTTGTGAT) – ACMG Classification: Pathogenic (18 pts)

Variant summary

Our verdict is Pathogenic. The variant received 18 ACMG points: 18P and 0B. PVS1PM2PP5_Very_Strong

The NM_000543.5(SMPD1):c.10_11insTTGTGATGCT(p.Tyr4PhefsTer51) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,460,032 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Likely pathogenic (★★).

Frequency

Genomes: not found (cov: 33)

Exomes 𝑓: 0.0000014 ( 0 hom. )

Consequence

SMPD1
NM_000543.5 frameshift

Scores

Not classified

Clinical Significance

Likely pathogenic criteria provided, multiple submitters, no conflicts P:2

Conservation

PhyloP100: 0.336

Publications

0 publications found

Variant links:

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 Gene-Disease associations (from GenCC):

acid sphingomyelinase deficiency
Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
Niemann-Pick disease
Inheritance: AR Classification: DEFINITIVE Submitted by: Myriad Women’s Health
Niemann-Pick disease type A
Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Genomics England PanelApp, Orphanet, G2P
Niemann-Pick disease type B
Inheritance: AR Classification: STRONG, SUPPORTIVE Submitted by: Genomics England PanelApp, Orphanet, Labcorp Genetics (formerly Invitae)

SMPD1 links:

LOC124902624 (HGNC:):

LOC124902624 links:

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ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 18 ACMG points.

PVS1

Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant located near the start codon (<100nt), not predicted to undergo nonsense mediated mRNA decay. There are 380 pathogenic variants in the truncated region.

PM2

Very rare variant in population databases, with high coverage;

PP5

Variant 11-6390605-C-CGCTTTGTGAT is Pathogenic according to our data. Variant chr11-6390605-C-CGCTTTGTGAT is described in ClinVar as [Likely_pathogenic]. Clinvar id is 2679041.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 link	c.10_11insTTGTGATGCT	p.Tyr4PhefsTer51	frameshift_variant	Exon 1 of 6	ENST00000342245.9	NP_000534.3	P17405-1Q59EN6

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SMPD1	ENST00000342245.9 link	c.10_11insTTGTGATGCT	p.Tyr4PhefsTer51	frameshift_variant	Exon 1 of 6	1	NM_000543.5	ENSP00000340409.4		P17405-1

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

0.00000137

AC:

AN:

1460032

Hom.:

Cov.:

AF XY:

0.00000275

AC XY:

AN XY:

726368

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33460

American (AMR)

AF:

0.00

AC:

AN:

44646

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26080

East Asian (EAS)

AF:

0.00

AC:

AN:

39644

South Asian (SAS)

AF:

0.00

AC:

AN:

86160

European-Finnish (FIN)

AF:

0.00

AC:

AN:

52400

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5744

European-Non Finnish (NFE)

AF:

0.00000180

AC:

AN:

1111610

Other (OTH)

AF:

0.00

AC:

AN:

60288

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.450

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

Cov.:

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

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

Pathogenic:1

Jan 24, 2024

Fulgent Genetics, Fulgent Genetics

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Niemann-Pick disease, type A

Pathogenic:1

Jan 04, 2024

Baylor Genetics

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

PhyloP100

0.34

Splicing

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

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11-6390605-C-CGCTTTGTGAT

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over