Genetic Variant SMPD4:p.Thr779Met (chr2-130152703-G-A) – ACMG Classification: Likely_benign (-5 pts)

Variant summary

Our verdict is Likely benign. The variant received -5 ACMG points: 0P and 5B. BP4BS2

The NM_017951.5(SMPD4):c.2336C>T(p.Thr779Met) variant causes a missense change. The variant allele was found at a frequency of 0.0000431 in 1,576,744 control chromosomes in the GnomAD database, including 2 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

Frequency

Genomes: 𝑓 0.00012 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000034 ( 2 hom. )

Consequence

SMPD4
NM_017951.5 missense

Scores

Clinical Significance

Uncertain significance criteria provided, single submitter U:1

Conservation

PhyloP100: 6.93

Publications

0 publications found

Variant links:

Genes affected

SMPD4 (HGNC:32949): (sphingomyelin phosphodiesterase 4) The protein encoded by this gene is a sphingomyelinase that catalyzes the hydrolysis of membrane sphingomyelin to form phosphorylcholine and ceramide. This gene is activated by DNA damage, cellular stress, and tumor necrosis factor, but it is downregulated by wild-type p53. The encoded protein localizes to the endoplasmic reticulum and Golgi network. [provided by RefSeq, Mar 2017]

SMPD4 Gene-Disease associations (from GenCC):

neurodevelopmental disorder with microcephaly, arthrogryposis, and structural brain anomalies
Inheritance: AR Classification: STRONG, MODERATE Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics, G2P

SMPD4 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_benign. The variant received -5 ACMG points.

BP4

Computational evidence support a benign effect (MetaRNN=0.31361175).

BS2

High Homozygotes in GnomAdExome4 at 2 AR gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SMPD4	NM_017951.5 link	c.2336C>T	p.Thr779Met	missense_variant	Exon 20 of 20	ENST00000680298.1	NP_060421.3	Q9NXE4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SMPD4	ENST00000680298.1 link	c.2336C>T	p.Thr779Met	missense_variant	Exon 20 of 20		NM_017951.5	ENSP00000506463.1		A0A7P0TB24

Frequencies

GnomAD3 genomes

AF:

0.000125

AC:

AN:

152208

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.000338

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000196

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.000207

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000511

AC:

AN:

176212

AF XY:

0.0000635

show subpopulations

Gnomad AFR exome

AF:

0.000200

Gnomad AMR exome

AF:

0.0000381

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.0000781

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000276

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000344

AC:

AN:

1424418

Hom.:

Cov.:

AF XY:

0.0000383

AC XY:

AN XY:

705310

show subpopulations

African (AFR)

AF:

0.000552

AC:

AN:

32624

American (AMR)

AF:

0.0000259

AC:

AN:

38564

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

25430

East Asian (EAS)

AF:

0.00

AC:

AN:

37604

South Asian (SAS)

AF:

0.000110

AC:

AN:

81972

European-Finnish (FIN)

AF:

0.00

AC:

AN:

49948

Middle Eastern (MID)

AF:

0.00

AC:

AN:

4822

European-Non Finnish (NFE)

AF:

0.0000110

AC:

AN:

1094516

Other (OTH)

AF:

0.000153

AC:

AN:

58938

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.497

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

AF:

0.000125

AC:

AN:

152326

Hom.:

Cov.:

AF XY:

0.0000805

AC XY:

AN XY:

74492

show subpopulations

African (AFR)

AF:

0.000337

AC:

AN:

41576

American (AMR)

AF:

0.000196

AC:

AN:

15306

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3470

East Asian (EAS)

AF:

0.00

AC:

AN:

5180

South Asian (SAS)

AF:

0.000207

AC:

AN:

4828

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10624

Middle Eastern (MID)

AF:

0.00

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.0000147

AC:

AN:

68022

Other (OTH)

AF:

0.00

AC:

AN:

2114

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.472

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Alfa

AF:

0.0000712

Hom.:

Bravo

AF:

0.000121

ExAC

AF:

0.0000590

AC:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

LINK: link

Submissions by phenotype

Inborn genetic diseases

Uncertain:1

Mar 28, 2025

Ambry Genetics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The c.2453C>T (p.T818M) alteration is located in exon 20 (coding exon 20) of the SMPD4 gene. This alteration results from a C to T substitution at nucleotide position 2453, causing the threonine (T) at amino acid position 818 to be replaced by a methionine (M). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.12

BayesDel_addAF

Benign

-0.12

BayesDel_noAF

Benign

-0.12

CADD

Uncertain

(source)

DANN

Uncertain

1.0

Eigen

Uncertain

0.51

Eigen_PC

Uncertain

0.39

FATHMM_MKL

Uncertain

0.93

LIST_S2

Uncertain

0.90

D;D;D

M_CAP

Benign

0.062

MetaRNN

Benign

0.31

T;T;T

MetaSVM

Uncertain

-0.11

PhyloP100

6.9

PrimateAI

Uncertain

0.75

PROVEAN

Uncertain

-3.4

D;D;D

REVEL

Uncertain

0.41

Sift

Uncertain

0.012

D;D;T

Sift4G

Uncertain

0.033

D;D;D

Vest4

0.67

MVP

0.39

MPC

0.93

ClinPred

0.80

GERP RS

4.1

Varity_R

0.16

gMVP

0.63

Mutation Taster

=64/36

polymorphism

(source)

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

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2-130152703-G-A

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over