Although the lack of COL4A5 in XLAS may cause negative IF result for collagen IV α5 chain and basket weave in GBM, and animal models of AS created by disruption of Col4 genes uniformly showed abnormalities in GBM similar to human AS and glomerular sclerosis16–19, the linkage between “basket weave” and progressive kidney disease is not well characterized. This evidence concerns the gene COL4A5 and X-linked hydrocephalus with stenosis of the aqueduct of Sylvius.