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It's not clear what causes Hirschsprung's disease. It sometimes occurs in families and may in some cases be associated with a genetic mutation.

Hirschsprung's disease occurs when nerve cells in the colon don't form completely. Nerve cells are critical to the functioning of the colon. They control the regular muscle contractions that keep food moving through the bowels.

As a baby develops before birth, bundles of nerve cells (ganglia) normally begin to form between the muscle layers along the length of the colon. This process begins at the top of the colon and ends at the bottom (rectum). In children who have Hirschsprung's disease, the nerve-growing process fails to finish. Most commonly, ganglia fail to form (aganglia) in the last segment of the colon — the rectum and the sigmoid colon. Sometimes aganglia affects the entire colon and even part of the small intestine.

Mar. 28, 2013