COL4A5 and X-linked hydrocephalus with stenosis of the aqueduct of Sylvius: We herein report 2 Japanese patients with X-linked Alport syndrome (XLAS), with a novel variant in COL4A5. Patient 1 was a 16-year-old Japanese girl with a history of microscopic hematuria, without proteinuria, renal dysfunction, deafness, or ocular abnormalities.