<s>[INST] context: Hirschsprung's disease is due to defective neural crest cell migration from cecum to rectum resulting in congenital absence of ganglion cells in the myenteric and submucosal plexuses of the bowel wall Hirschsprung's disease - Hirschsprung disease, or congenital aganglionic megacolon, is a developmental disorder (neurocristopathy) of the enteric nervous system Pathophysiology - The enteric neuronal plexus develops from neural crest cells that migrate into the bowel wall during embryogenesis. Hirschsprung disease occurs when the normal migration of neural crest cells from cecum to rectum is disrupted. This produces a distal intestinal segment that lacks both the Meissner submucosal plexus and the Auerbach myenteric plexus ("aganglionosis"), and thus fails to develop coordinated peristaltic contractions Clinical features - Delayed passage of Meconium Bilious vomiting Abdominal distension Complications like Intestinal perforation and Rectal bleeding Diagnosis - A) Barium enema - Contracted involved segment become narrow Dilated normal proximal segment B) Intestinal Biopsy - gives definite diagnosis Absence of Ganglion cells Nerve trunk hyperophy Increased Acetylcholinesterase activity in involved segment Rx - Surgery (Surgical resection of involved segment f/b anastomosis of Normal segments) [/INST] question: Which of the following is a cause of Hirschsprung disease in a patient ? | options: A: Failure of migration of neural crest cells B: Excessive peristalsis of the affected pa of the gut C: Failure of involution of vitelline duct D: Obstruction secondary to an infectious agent | answer: A </s>