This is the case of a family with XLAS, in which the coinheritance of COL4A5 mutations and homozygous MYO1E variants were associated with more severe kidney disease [29], and can explain a highly variable renal phenotype, inexplicable by conventional pedigree analysis. This evidence concerns the gene COL4A5 and X-linked hydrocephalus with stenosis of the aqueduct of Sylvius.