Irregular bladder smooth muscle actin-gamma 2 expression in ACTG2 mutation-associated Megacystis Microcolon Intestinal Hypoperistalsis Syndrome (MMIHS): A case report

Abstract

Peter Heinz-Erian*, Elisabeth Bruder, Andreas Janecke, Peter Rehder, Heinz Zoller, Bettina Zelger, Markus Pirklbauer and Thomas Müller

The majority of published cases of Megacystis Microcolon Intestinal Hypoperistalsis Syndrome (MMIHS), a disorder of smooth muscle function of hollow visceral organs is associated with mutations in the actin gamma2 (ACTG2) gene on chromosome 2p13. While alterations in smooth muscle actin histology have been described for the gastrointestinal tract no such information is available for urogenital organs of patients with ACTG2 mutation-based MMIHS. We report the first description of actin gamma2 pathohistology in bladder smooth muscle of a male MMIHS-patient bearing a de novo ACTG2-mutation (c.770G>A; p.R257H) who suffered from voiding insufficiency due to severely deficient bladder contractility as demonstrated by video-urodynamic investigations. Our findings are a further contribution to the elucidation of pathogenic mechanisms of functional myopathic bladder atony.