11-6392120-A-C

Position:

• chr11-6392120-A-C

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_000543.5(SMPD1):​c.1055A>C​(p.Glu352Ala) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000041 in 1,461,892 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 14/20 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 0.0000041 (0 hom.)
• Consequence: SMPD1 NM_000543.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 2.91

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 (HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.17982897).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
SMPD1	NM_000543.5	c.1055A>C	p.Glu352Ala	missense_variant	2/6	ENST00000342245.9	NP_000534.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
SMPD1	ENST00000342245.9	c.1055A>C	p.Glu352Ala	missense_variant	2/6	1	NM_000543.5	ENSP00000340409.4

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251076 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135728

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: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000882

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000410 AC: 6 AN: 1461892 Hom.: 0 Cov.: 36 AF XY: 0.00000275 AC XY: 2 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: 0.00000540

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 31

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Inborn genetic diseases Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Jun 30, 2024

The c.1055A>C (p.E352A) alteration is located in exon 2 (coding exon 2) of the SMPD1 gene. This alteration results from a A to C substitution at nucleotide position 1055, causing the glutamic acid (E) at amino acid position 352 to be replaced by an alanine (A). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

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

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Sep 07, 2022

This sequence change replaces glutamic acid, which is acidic and polar, with alanine, which is neutral and non-polar, at codon 352 of the SMPD1 protein (p.Glu352Ala). This variant is present in population databases (rs771028947, gnomAD 0.0009%). This variant has not been reported in the literature in individuals affected with SMPD1-related conditions. ClinVar contains an entry for this variant (Variation ID: 581009). 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 not expected to disrupt SMPD1 protein function. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Sphingomyelin/cholesterol lipidosis Uncertain:1

Uncertain significance, no assertion criteria provided

clinical testing

Natera, Inc.

Sep 16, 2020

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.080
BayesDel_addAF	Uncertain	0.020	T
BayesDel_noAF	Benign	-0.21
CADD	Benign	16
DANN	Benign	0.95
Eigen	Benign	-0.13
Eigen_PC	Benign	-0.00032
FATHMM_MKL	Uncertain	0.80	D
LIST_S2	Benign	0.79	T;T
M_CAP	Benign	0.010	T
MetaRNN	Benign	0.18	T;T
MetaSVM	Benign	-1.0	T
PrimateAI	Benign	0.34	T
PROVEAN	Benign	-0.86	N;N
REVEL	Benign	0.26
Sift	Benign	0.45	T;T
Sift4G	Benign	0.70	T;T
Vest4		0.11
MVP		0.96
MPC		0.22
ClinPred		0.15	T
GERP RS		3.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1
Varity_R		0.092
gMVP		0.82

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs771028947; hg19: chr11-6413350;