Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM2PP3_Strong
The NM_024079.5(ALG8):c.824G>T(p.Gly275Val) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000657 in 152,166 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).
ALG8 (HGNC:23161): (ALG8 alpha-1,3-glucosyltransferase) This gene encodes a member of the ALG6/ALG8 glucosyltransferase family. The encoded protein catalyzes the addition of the second glucose residue to the lipid-linked oligosaccharide precursor for N-linked glycosylation of proteins. Mutations in this gene have been associated with congenital disorder of glycosylation type Ih (CDG-Ih). Alternatively spliced transcript variants encoding different isoforms have been identified. [provided by RefSeq, Jul 2008]
ALG8 congenital disorder of glycosylation Uncertain:1
Feb 21, 2023
Labcorp Genetics (formerly Invitae), Labcorp
Significance: Uncertain significance
Review Status: criteria provided, single submitter
Collection Method: clinical testing
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. 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 expected to disrupt ALG8 protein function. This variant has not been reported in the literature in individuals affected with ALG8-related conditions. This variant is present in population databases (no rsID available, gnomAD 0.007%). This sequence change replaces glycine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 275 of the ALG8 protein (p.Gly275Val). -