COL4A1 and autosomal dominant familial hematuria-retinal arteriolar tortuosity-contractures syndrome: HANAC syndrome has been proposed as a clinical sub-entity within COL4A1/COL4A2 disease (Alamowitch et al., 2009), resulting from mutations located in or close to the integrin-binding CB3 region of the collagen protomer predicted to affect integrin signalling (Plaisier et al., 2010).