MID1 and Opitz G/BBB syndrome: The MID1 gene encodes a microtubule-associated RING-Bbox-Coiled-coil (RBCC) protein and Cainarca et al. suggest that midin is involved in the formation of multiprotein structures and that impaired association with these cytoskeletal structures causes the developmental defects of Opitz syndrome (Cainarca et al., 1999).