ClinVar

Description

This sequence change replaces glycine, which is neutral and non-polar, with arginine, which is basic and polar, at codon 171 of the COL4A5 protein (p.Gly171Arg). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with Alport syndrome (Invitae). ClinVar contains an entry for this variant (Variation ID: 447213). 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 COL4A5 protein function with a positive predictive value of 95%. This variant disrupts the triple helix domain of COL4A5. Glycine residues within the Gly-Xaa-Yaa repeats of the triple helix domain are required for the structure and stability of fibrillar collagens (PMID: 7695699, 8218237, 19344236). In COL4A5, missense variants at these glycine residues are significantly enriched in individuals with disease (PMID: 23720012, 27627812) compared to the general population (ExAC). This variant disrupts the p.Gly171 amino acid residue in COL4A5. Other variant(s) that disrupt this residue have been observed in individuals with COL4A5-related conditions (Invitae), which suggests that this may be a clinically significant amino acid residue. 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.