A congenital disorder in which part of the colon lacks nerve cells and therefore is unable to relax. The result is chronic constipation and distention of the abdomen. The disorder affects about one in 5000 U.S. newborns but can be treated with surgery.

Dr. William Pavan, of the National Human Genome Research Institute's Laboratory of Genetic Disease Research, defines Hirschsprung's disease.

Related terms: cell, gene, mutation.