Our verdict is Uncertain significance. Variant got 1 ACMG points: 2P and 1B. PM2BS1_Supporting
The NM_006279.5(ST3GAL3):c.1070A>T(p.Glu357Val) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000148 in 1,614,070 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★★).
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]
Verdict is Uncertain_significance. Variant got 1 ACMG points.
PM2
Very rare variant in population databases, with high coverage;
BS1
Variant frequency is greater than expected in population nfe. gnomad4_exome allele frequency = 0.000159 (232/1461846) while in subpopulation NFE AF= 0.000203 (226/1112008). AF 95% confidence interval is 0.000181. There are 0 homozygotes in gnomad4_exome. There are 115 alleles in male gnomad4_exome subpopulation. Median coverage is 32. This position pass quality control queck. Existence of Clinvar submissions makes me limit the strength of this signal to Supporting
Genetic Services Laboratory, University of Chicago
Significance: Uncertain significance
Review Status: criteria provided, single submitter
Collection Method: clinical testing
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Inborn genetic diseases Uncertain:1
Dec 21, 2022
Ambry Genetics
Significance: Uncertain significance
Review Status: criteria provided, single submitter
Collection Method: clinical testing
The c.1070A>T (p.E357V) alteration is located in exon 12 (coding exon 11) of the ST3GAL3 gene. This alteration results from a A to T substitution at nucleotide position 1070, causing the glutamic acid (E) at amino acid position 357 to be replaced by a valine (V). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -
Early infantile epileptic encephalopathy with suppression bursts Uncertain:1
Sep 24, 2022
Labcorp Genetics (formerly Invitae), Labcorp
Significance: Uncertain significance
Review Status: criteria provided, single submitter
Collection Method: clinical testing
This sequence change replaces glutamic acid, which is acidic and polar, with valine, which is neutral and non-polar, at codon 357 of the ST3GAL3 protein (p.Glu357Val). This variant is present in population databases (rs141947405, gnomAD 0.007%). This variant has not been reported in the literature in individuals affected with ST3GAL3-related conditions. ClinVar contains an entry for this variant (Variation ID: 436877). 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 ST3GAL3 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. -
Intellectual disability, autosomal recessive 12;C3554316:Developmental and epileptic encephalopathy, 15 Uncertain:1
Oct 31, 2018
Fulgent Genetics, Fulgent Genetics
Significance: Uncertain significance
Review Status: criteria provided, single submitter