The COL4A5 gene is located on the X chromosome. This gene codes for Type IV collagen, which is one of the components of the basement membrane. The glomerular basement membrane of the kidneys is responsible for filtering out fluid and retaining blood and proteins. Defects in the membrane structure lead to abnormalities in the function of this filtering process, leading to proteinuria and hematuria. Defects in collagen also lead to abnormalities in the shape of the lens and structure of the inner ear, leading to ocular and hearing abnormalities.