MYH11 mutations have previously been associated with Megacystis-Microcolon-Intestinal Hypoperistalsis Syndrome, however, Yetman and Starr [59] describe a case where an MYH11 frameshift mutation was present in a suspected Multisystemic Smooth Muscle Dysfunction Syndrome / Megacystis-Microcolon-Intestinal Hypoperistalsis Syndrome patient without the causal ACTA2 gene mutations, proposing a novel recessive MYH11 presentation. The gene discussed is ACTA2; the disease is Megacystis.