Analysis of genetic control of chylous ascites in ragged mice.

Chylous ascites is a disorder visible as a white fluid in the peritoneal cavity of suckling mice. It is due to inadequate lymphatic drainage from the small intestine. An initial genetic study showed it to be a pleiotropic effect of ragged, Ra. There were four main studies. These involved seven major mutants segregating with ragged. Four of the mutants had no effect on chylous ascites, but two mutants linked with ragged, and one unlinked, showed a complex situation involving enhancement, inhibition, epistacy and other interactions. The overall phenotypic effects which these mutants are known to have do not explain how they produce their interaction with ragged in terms of chylous ascites. The studies also indicate the existence of a single major modifier controlling penetrance and expression, and there is evidence for cumulatively acting minor modifiers. In neonates the male sex is more liable to chylous ascites, and in adults this condition affects fertility and fecundity.