Among these diseases, X-linked Alport syndrome (XLAS) is a hematuric nephropathy affecting the glomerular basement membrane (GBM) secondary to pathogenic variations in the COL4A5 gene encoding the α5 subunit of type IV collagen [α5(IV)]. The gene discussed is COL4A5; the disease is X-linked hydrocephalus with stenosis of the aqueduct of Sylvius.