ENST00000361392.9:c.119G>A

Variant names:

• chr1-43736381-G-A
• ENST00000361392.9:c.119G>A

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PM2 PP3_Moderate PP5_Moderate

The ENST00000361392.9(ST3GAL3):​c.119G>A​(p.Ser40Asn) variant causes a missense change. The variant allele was found at a frequency of 0.000000684 in 1,461,878 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. S40G) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: ST3GAL3 ENST00000361392.9 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 6.71
• Publications: 0 publications found

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

ENSG00000284989 (HGNC:):

ACMG classification

Our verdict: Likely_pathogenic. The variant received 6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 1-43736381-G-A is Pathogenic according to our data. Variant chr1-43736381-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 1477582.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
ST3GAL3	NM_006279.5	c.118+1G>A		splice_donor_variant, intron_variant	Intron 2 of 11	ENST00000347631.8	NP_006270.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
ST3GAL3	ENST00000347631.8	c.118+1G>A		splice_donor_variant, intron_variant	Intron 2 of 11	5	NM_006279.5	ENSP00000317192.6
ENSG00000284989	ENST00000645057.1	n.*1440+1G>A		splice_donor_variant, intron_variant	Intron 16 of 25			ENSP00000494063.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461878 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 727242

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44722

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26134

East Asian (EAS) AF: 0.00 AC: 0 AN: 39698

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53418

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1112004

Other (OTH) AF: 0.00 AC: 0 AN: 60396

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Developmental and epileptic encephalopathy Pathogenic:1

Jul 21, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. This variant has not been reported in the literature in individuals affected with ST3GAL3-related conditions. This variant is not present in population databases (ExAC no frequency). This sequence change affects a donor splice site in intron 2 of the ST3GAL3 gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in ST3GAL3 are known to be pathogenic (PMID: 31584066). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Uncertain	0.034	T
BayesDel_noAF	Benign	-0.36
CADD	Pathogenic	34
DANN	Uncertain	0.99
Eigen	Uncertain	0.34
Eigen_PC	Uncertain	0.48
FATHMM_MKL	Uncertain	0.97	D
M_CAP	Benign	0.035	D
PhyloP100		6.7
ClinPred		0.90	D
GERP RS		5.9
PromoterAI		-0.047	Neutral
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Mutation Taster		=7/93	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.96		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.69		Position offset: 44
DS_DL_spliceai		0.96		Position offset: -1

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

Other links and lift over

hg19: chr1-44202052; COSMIC: COSV53522485;