occurs in occurs in phenotype affects entity basement membrane biosynthetic process impaired basement membrane formation MP:0003044 impaired basement lamina formation defect in the development of the extracellular supportive tissue closely adjacent to the basal surface of the epithelium of muscle cells, fat cells and Schwann cells, which is comprised of type IV collagen, laminin, and sulfated proteoglycans and other components MPheno.ontology abnormal basement membrane morphology abnormal metabolism absent biosynthetic process in basement membrane