MID1 and X-linked Opitz G/BBB syndrome: Mid1 encodes a member of the interferon-inducible tripartite motif family of proteins, (TRIM18; midline 1), and mutations in this cytoplasmic microtubule-associated protein are causally implicated in X-linked Opitz G/BBB syndrome characterized by abnormalities such as cleft lip, heart defects and agenesis of the corpus callosum (79).