Association of megacolon with a new dominant spotting gene (Dom) in the mouse.

A new semidominant mutation in the mouse is described. In heterozygotes it produces white spotting and a deficiency of myenteric ganglion cells in the colon and, in homozygotes it is lethal prior to 13 days of gestation. The mutation, called dominant megacolon, symbol Dom, is located on chromosome (chr) 15, 20.6 +/- 1.6 units proximal to Ca. Hairy ears, Eh, a semidominant gene also on chr 15 is shown to have a suppressing effect on crossing over in this section of chr 15.