Megacystis-microcolon-intestinal hypoperistalsis syndrome

Megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS), also known as Berdon syndrome, is a severe congenital disorder affecting the smooth muscle function of the bladder and intestines. It is characterized by three cardinal features: a massively enlarged, non-obstructed urinary bladder (megacystis), an abnormally small colon (microcolon), and decreased or absent intestinal peristalsis (the wave-like muscle contractions that move food through the digestive tract). The condition is typically detected prenatally or at birth, often presenting with abdominal distension, failure to pass meconium, and bilious vomiting in the neonatal period. Hydronephrosis (swelling of the kidneys) is frequently observed due to impaired bladder emptying. MMIHS primarily affects the gastrointestinal and urinary systems. The underlying pathology involves dysfunction of visceral smooth muscle cells, and mutations in the ACTG2 gene (encoding gamma-2 smooth muscle actin) have been identified as a major cause. Mutations in MYH11 and LMOD1 have also been implicated in some cases. The condition leads to functional intestinal obstruction, making affected individuals unable to tolerate enteral feeding. Most patients require long-term total parenteral nutrition (TPN) for survival, and some may be considered for intestinal or multivisceral transplantation. The prognosis for MMIHS remains poor despite advances in supportive care. Complications of long-term TPN, including liver disease and recurrent central line infections, contribute significantly to morbidity and mortality. Many affected infants do not survive beyond the first year of life, although improved nutritional support and transplantation have extended survival in some cases. There is currently no curative treatment, and management is primarily supportive, focusing on nutritional optimization, urinary drainage, and prevention of complications.

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