Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2
The NM_003193.5(TBCE):c.1438C>T(p.Arg480Cys) variant causes a missense change. The variant allele was found at a frequency of 0.0000062 in 1,614,008 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R480H) has been classified as Uncertain significance.
TBCE (HGNC:11582): (tubulin folding cofactor E) Cofactor E is one of four proteins (cofactors A, D, E, and C) involved in the pathway leading to correctly folded beta-tubulin from folding intermediates. Cofactors A and D are believed to play a role in capturing and stabilizing beta-tubulin intermediates in a quasi-native confirmation. Cofactor E binds to the cofactor D/beta-tubulin complex; interaction with cofactor C then causes the release of beta-tubulin polypeptides that are committed to the native state. Two transcript variants encoding the same protein have been found for this gene. [provided by RefSeq, Jul 2008]
B3GALNT2 (HGNC:28596): (beta-1,3-N-acetylgalactosaminyltransferase 2) This gene encodes a member of the glycosyltransferase 31 family. The encoded protein synthesizes GalNAc:beta-1,3GlcNAc, a novel carbohydrate structure, on N- and O-glycans. Alternatively spliced transcript variants that encode different isoforms have been described. [provided by RefSeq, Mar 2013]
Review Status: criteria provided, single submitter
Collection Method: clinical testing
This sequence change replaces arginine, which is basic and polar, with cysteine, which is neutral and slightly polar, at codon 480 of the TBCE protein (p.Arg480Cys). This variant is present in population databases (rs138749985, gnomAD 0.004%). This variant has not been reported in the literature in individuals affected with TBCE-related conditions. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive. 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. -