COL4A6 and steroid-resistant nephrotic syndrome: Besides AS, COL4A3/COL4A4 mutations are associated with kidney disorders including diabetic kidney disease [13], focal segmental sclerosis [14] and steroid-resistant nephrotic syndrome [15], while COL4A5/COL4A6 mutations affect axogenesis in zebrafish [16], and COL4A6 mutations can cause non-syndromic hearing loss [17], indicating a growing role of these mutations in disease.