Genetic Variant ST3GAL3:p.Gly199* (chr1-43930172-G-T) – ACMG Classification: Uncertain_significance (4 pts)

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PVS1_ModeratePM2

The ENST00000372367.5(ST3GAL3):c.595G>T(p.Gly199*) variant causes a stop gained change. The variant allele was found at a frequency of 0.000000684 in 1,461,790 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

Frequency

Genomes: not found (cov: 33)

Exomes 𝑓: 6.8e-7 ( 0 hom. )

Consequence

ST3GAL3
ENST00000372367.5 stop_gained

Scores

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: 4.70

Publications

0 publications found

Variant links:

Genes affected

ST3GAL3 (HGNC:10866): (ST3 beta-galactoside alpha-2,3-sialyltransferase 3) The protein encoded by this gene is a type II membrane protein that catalyzes the transfer of sialic acid from CMP-sialic acid to galactose-containing substrates. The encoded protein is normally found in the Golgi apparatus but can be proteolytically processed to a soluble form. This protein is a member of glycosyltransferase family 29. Mutations in this gene have been associated with a form of autosomal recessive nonsymdromic cognitive disability as well as infantile epileptic encephalopathy. Multiple transcript variants encoding several different isoforms have been found for this gene. [provided by RefSeq, Jul 2017]

ST3GAL3 Gene-Disease associations (from GenCC):

developmental and epileptic encephalopathy, 15
Inheritance: AR Classification: STRONG, LIMITED Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics
intellectual disability, autosomal recessive 12
Inheritance: AR Classification: STRONG Submitted by: G2P
complex neurodevelopmental disorder
Inheritance: AR Classification: MODERATE Submitted by: ClinGen
infantile spasms
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
autosomal recessive non-syndromic intellectual disability
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ST3GAL3 links:

ENSG00000284989 (HGNC:):

ENSG00000284989 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 4 ACMG points.

PVS1

Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most exon, not predicted to undergo nonsense mediated mRNA decay. Fraction of 0.0182 CDS is truncated, and there are 0 pathogenic variants in the truncated region.

PM2

Very rare variant in population databases, with high coverage;

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
ST3GAL3	NM_006279.5 link	c.1079G>T	p.Arg360Leu	missense_variant	Exon 12 of 12	ENST00000347631.8	NP_006270.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein
ST3GAL3	ENST00000347631.8 link	c.1079G>T	p.Arg360Leu	missense_variant	Exon 12 of 12	5	NM_006279.5	ENSP00000317192.6
ENSG00000284989	ENST00000645057.1 link	n.*2401G>T		non_coding_transcript_exon_variant	Exon 26 of 26			ENSP00000494063.1
ENSG00000284989	ENST00000645057.1 link	n.*2401G>T		3_prime_UTR_variant	Exon 26 of 26			ENSP00000494063.1

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

6.84e-7

AC:

AN:

1461790

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

727204

show subpopulations

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.00

AC:

AN:

33480

American (AMR)

AF:

0.00

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26136

East Asian (EAS)

AF:

0.00

AC:

AN:

39700

South Asian (SAS)

AF:

0.0000116

AC:

AN:

86250

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53382

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5722

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1112012

Other (OTH)

AF:

0.00

AC:

AN:

60384

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.375

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

Cov.:

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.21

BayesDel_addAF

Uncertain

0.096

BayesDel_noAF

Benign

-0.11

CADD

Benign

(source)

DANN

Uncertain

0.98

Eigen

Benign

-0.24

Eigen_PC

Benign

-0.11

FATHMM_MKL

Uncertain

0.86

PhyloP100

4.7

Vest4

0.17

ClinPred

0.93

GERP RS

3.6

Varity_R

0.16

Mutation Taster

=88/112

disease causing

(source)

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over