COL4A5 and Alport syndrome: Mutations in COL4A6 alone have not been related to Alport syndrome [22,23], but a COL4A6 mutation is linked to hereditary hearing loss, which is a more restricted symptom compared to Alport syndrome [37], implying that the Col4a5/Col4a6 complex has a more limited role in BM integrity in humans than in zebrafish.