Collagen Genes-Related Glomerular Disease.

Alport syndrome is a genetic kidney disease caused by variants in genes encoding the ⍺3, ⍺4, or ⍺5 isoforms of type IV collagen leading to hematuria, proteinuria, and CKD in many, but not all, affected patients. Variants in type IV collagen genes have been increasingly recognized and may affect up to 1 in 106 people. There is wide phenotypic variability depending on inheritance pattern (autosomal recessive vs autosomal dominant vs X-linked vs digenic), sex of the affected individual, specific variant, and other as yet unidentified factors. This review examines the genotype/phenotype correlation for individuals with type IV collagen variants. We also review recommendations for who should be tested for type IV collagen variants as well as strategies for predicting pathogenicity of a variant once identified. Finally, we provide recommendations for monitoring of individuals with type IV collagen variants.