<prompt> Not true regarding Hirschsprung disease is -Autosomal dominantAbsent ganglionic cells in myentric plexusAbsent ganglionic cells in submucus plexusRectal biopsy is diagnostic  <response>: Hirschprungs ds or Aganglionic megacolon or Congenital megacolon is a congenital disorder dt absence of ganglion cells in the neural plexus ie both myenteric Auerbachs and submucosal Meissners plexus of the intestinal wall.There is accompanying hypertrophy of the nerve trunks.MC site is a rectosigmoid colon. or Rectum, more specificallyThe Clinical picture varies from acute intestinal obstruction in neonates to chronic constipation in later life.One imp feature which distinguishes Hirschprungs disease from other types of constipation is that faecal soiling is not a feature of HD.M: F ratio is 4: 1Diagnosis:Barium enema: The initial diagnostic step in a newborn with radiographic evidence of a distal bowel obstruction is a barium enema. In a normal barium enema study, the rectum is wider than the sigmoid colon. In patients with Hirschsprungs disease, this relationship is reversed.Rectal biopsy -Diagnosis can be confirmed by a full thickness rectal biopsy. A rectal biopsy is a gold standard for the diagnosis of Hirschsprungs disease.The histopathologic features of Hirschsprungs disease are:Absent ganglia,hypertrophied nerve trunks, andincreased acetylcholinesterase stainingAnorectal manometry -is a useful screening test in constipated young child or adult who is otherwise fit.Treatment of choiceis a pull-through procedure in which normally innervated colon is anastomosed to the distal rectum just above the internal sphincter, thus bypassing the contracted aganglionic segment and restoring normal defecation.Option aMost of the cases are sporadic, Familial cases also occur but their inheritance pattern is not clear. 