ClinVar Genomic variation as it relates to human health

This sequence change replaces glycine, which is neutral and non-polar, with serine, which is neutral and polar, at codon 307 of the COL4A5 protein (p.Gly307Ser). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with COL4A5-related conditions. ClinVar contains an entry for this variant (Variation ID: 1522243). 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). 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.

Based on the classification scheme VCGS_Germline_v1.3.4, this variant is classified as Pathogenic. The following criteria are met: 0103 - Dominant negative and loss of function are known mechanisms of disease in this gene and are associated with X-linked Alport syndrome 1 (MIM#301050). Dominant negative is caused mostly by glycine substitutions that affect the conformation of the protein, and loss of function can be caused by either protein truncating or missense variants (PMID: 24046192, PMID: 12028435). (I) 0110 - This gene is associated with X-linked dominant disease. Males are typically more severely affected than females (PMID: 19965530). (I) 0115 - Variants in this gene are known to have variable expressivity. There is intrafamilial variability among affected carrier females, possibly due to variable X-inactivation (PMID: 14514738). (I) 0200 - Variant is predicted to result in a missense amino acid change from glycine to serine. (I) 0251 - This variant is heterozygous. (I) 0301 - Variant is absent from gnomAD (both v2 and v3). (SP) 0501 - Missense variant consistently predicted to be damaging by multiple in silico tools and highly conserved with a minor amino acid change. (SP) 0601 - Variant is located in the well-established triple helical G-X-Y repeat region, and affects a glycine residue (DECIPHER). (SP) 0704 - Another missense variant comparable to the one identified in this case has limited previous evidence for pathogenicity. p.(Gly307Asp) has previously been reported as likely pathogenic and pathogenic (ClinVar, LOVD). It has also been reported in at least one male adult with Alport syndrome (PMID: 26809805). (SP) 0802 - This variant has moderate previous evidence of pathogenicity in unrelated individuals. This variant has been reported as likely pathogenic (ClinVar, LOVD). It has also been reported in at least one family with glomerulopathy where onset of symptoms were reported to be in adulthood (PMID: 34746741). (SP) 0905 - No published segregation evidence has been identified for this variant. (I) 1007 - No published functional evidence has been identified for this variant. (I) Legend: (SP) - Supporting pathogenic, (I) - Information, (SB) - Supporting benign