Hirschsprung (HSCR) disease (congenital megacolon) is a birth defect affecting the motility of the bowel. These babies suffer from severe constipation and intestinal obstruction because the nerve cells which co-ordinate bowel movements are absent. It is a global problem but is particularly prevalent in Asia, affecting 1 in 3,000 babies. It is known that DNA changes disrupting the function of RET gene cause a severe form of HSCR disease (total colonic aganglionosis). However, 80% of HSCR patients have short-segment HSCR disease (S-HSCR), which has not been associated with genetic factors.