The degective migration of neural crest cells results in
Hirschsprung's disease (congenital mega colon) Hirschsprung's disease is characterised by the congenital absence of intramural ganglion cells (aganglionosis) and the presence of hyperophic nerves in the distal large bowel. The absence of ganglion cells is due to a failure of migration of vagal neural crest cells into the developing gut. The affected gut is in spasm, causing a functional bowel obstruction. The aganglionosis is restricted to the rectum and sigmoid colon in 75% of patients (sho segment), involves the proximal colon in 15% (long segment) and affects the entire colon and a poion of terminal ileum in 10% (total colonic aganglionosis) . A transition zone exists between the dilated, proximal, normally innervated bowel and the narrow, distal aganglionic segment.Hirschsprung's disease may be familial or associated with Down syndrome or other genetic disorders. Gene mutations have been identified on chromosome 10 (involving the RET proto-oncogene) and on chromosome 13 in some patients. Hirschsprung's disease typically presents in the neonatal period with delayed passage of meconium, abdominal distension and bilious vomiting but it may not be diagnosed until later in childhood or even adult life, when it manifests as severe chronic constipation. Enterocolitis is a potentially fatal complication. The diagnosis requires an adequate rectal biopsy and an experienced pathologist. A contrast enema may show the narrow aganglionic segment, a cone and the dilated proximal bowel. Surgery aims to remove the aganglionic segment and 'pull-through' ganglionic bowel to the anus (e.g. Swenson, Duhamel, Soave and transanal procedures), and can be done in a single stage or in stages after first establishing a proximal stoma in normally innervated bowel. Most patients achieve good bowel control but a significant minority experience residual constipation and/or faecal incontinence or fuher enterocolitis. Ref: Bailey and love 27th edition Pgno : 136
Congenital megacolon
Albinism
Adrenogenital hypoplasia
Dentinogenesis imperfecta
Urology