Hirschsprung disease (HSCR, aganglionic megacolon) is the main genetic cause of functional intestinal obstruction with an incidence of 1/5000 live births. This developmental disorder is a neurocristopathy and is characterised by the absence of the enteric ganglia along a variable length of the intestine. In the last decades, the development of surgical approaches has dramatically decreased mortality and morbidity, which has allowed the emergence of familial cases. HSCR appeared to be a multifactorial malformation with low, sex dependent penetrance and variable expression according to the length of the aganglionic segment, suggesting the involvement of one or more gene(s) with low penetrance. So far, eight genes have been found to be involved in HSCR. This frequent congenital malformation now stands as a model for genetic disorders with complex patterns of inheritance.