Genetic Variant SMPD1:p.Phe333SerfsTer52 (chr11-6392055-TC-T) – ACMG Classification: Pathogenic (22 pts)

Variant summary

Our verdict is Pathogenic. The variant received 22 ACMG points: 22P and 0B. PVS1PS3PM2PP5_Very_Strong

The NM_000543.5(SMPD1):c.996delC(p.Phe333SerfsTer52) variant causes a frameshift change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000421 in 1,613,606 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Pathogenic (★★). ClinVar reports functional evidence for this variant: "SCV001422555: "In vitro functional studies provide some evidence that the p.Phe333Serfs variant may impact protein function (PMID:15877209" and additional evidence is available in ClinVar. Synonymous variant affecting the same amino acid position (i.e. P332P) has been classified as Likely benign. Variant results in nonsense mediated mRNA decay.

Frequency

Genomes: 𝑓 0.000013 ( 0 hom., cov: 31)

Exomes 𝑓: 0.000045 ( 0 hom. )

Consequence

SMPD1
NM_000543.5 frameshift

Scores

Not classified

Clinical Significance

Pathogenic criteria provided, multiple submitters, no conflicts P:13O:1

Conservation

PhyloP100: 7.54

Publications

19 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: Orphanet, Genomics England PanelApp, PanelApp Australia, G2P
Niemann-Pick disease type B
Inheritance: AR Classification: STRONG, SUPPORTIVE Submitted by: PanelApp Australia, Genomics England PanelApp, Orphanet, Labcorp Genetics (formerly Invitae)

SMPD1 links:

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ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 22 ACMG points.

PVS1

Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.

PS3

PS3 evidence extracted from ClinVar submissions: SCV001422555: "In vitro functional studies provide some evidence that the p.Phe333Serfs variant may impact protein function (PMID: 15877209; 9266408)."

PM2

Very rare variant in population databases, with high coverage;

PP5

Variant 11-6392055-TC-T is Pathogenic according to our data. Variant chr11-6392055-TC-T is described in ClinVar as Pathogenic. ClinVar VariationId is 2990.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000543.5. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
SMPD1	NM_000543.5	MANE Select	c.996delC	p.Phe333SerfsTer52	frameshift	Exon 2 of 6	NP_000534.3
SMPD1	NM_001007593.3		c.993delC	p.Phe332SerfsTer52	frameshift	Exon 2 of 6	NP_001007594.2	P17405-4
SMPD1	NM_001365135.2		c.996delC	p.Phe333SerfsTer48	frameshift	Exon 2 of 5	NP_001352064.1	P17405-2

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
SMPD1	ENST00000342245.9	TSL:1 MANE Select	c.996delC	p.Phe333SerfsTer52	frameshift	Exon 2 of 6	ENSP00000340409.4	P17405-1
SMPD1	ENST00000526280.1	TSL:1	c.183delC	p.Phe62fs	frameshift	Exon 1 of 4	ENSP00000436278.1	H0YEP5
SMPD1	ENST00000533123.5	TSL:1	n.996delC		non_coding_transcript_exon	Exon 2 of 5	ENSP00000435950.1	G3V1E1

Frequencies

GnomAD3 genomes

AF:

0.0000132

AC:

AN:

151720

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.000577

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

GnomAD2 exomes

AF:

0.0000557

AC:

AN:

251408

AF XY:

0.0000221

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00129

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00000879

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000451

AC:

AN:

1461886

Hom.:

Cov.:

AF XY:

0.0000413

AC XY:

AN XY:

727246

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33480

American (AMR)

AF:

0.00

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00191

AC:

AN:

26136

East Asian (EAS)

AF:

0.00

AC:

AN:

39700

South Asian (SAS)

AF:

0.00

AC:

AN:

86258

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53420

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.00000809

AC:

AN:

1112004

Other (OTH)

AF:

0.000116

AC:

AN:

60396

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.500

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.0000132

AC:

AN:

151720

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74064

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41250

American (AMR)

AF:

0.00

AC:

AN:

15238

Ashkenazi Jewish (ASJ)

AF:

0.000577

AC:

AN:

3464

East Asian (EAS)

AF:

0.00

AC:

AN:

5152

South Asian (SAS)

AF:

0.00

AC:

AN:

4816

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10556

Middle Eastern (MID)

AF:

0.00

AC:

AN:

314

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

67932

Other (OTH)

AF:

0.00

AC:

AN:

2086

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.500

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Alfa

AF:

0.000217

Hom.:

Bravo

AF:

0.0000227

ClinVar

ClinVar submissions

Significance:Pathogenic

Revision:criteria provided, multiple submitters, no conflicts

View on ClinVar

Pathogenic

VUS

Benign

Condition

Niemann-Pick disease, type A (5)

not provided (3)

Niemann-Pick disease, type A;C0268243:Niemann-Pick disease, type B (2)

Acid sphingomyelinase deficiency (1)

Niemann-Pick disease, type B (1)

Sphingomyelin/cholesterol lipidosis (2)

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

PhyloP100

7.5

Mutation Taster

=0/200

disease causing (ClinVar)

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.10

Details are displayed if max score is > 0.2

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

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over