Genetics, Vol 144, 1777-1785, Copyright © 1996


INVESTIGATIONS

Genetic Evaluation of Candidate Genes for the Mom1 Modifier of Intestinal Neoplasia in Mice

K. A. Gould, C. Luongo, A. R. Moser, M. K. McNeley, N. Borenstein, A. Shedlovsky, W. F. Dove, K. Hong, W. F. Dietrich and E. S. Lander
McArdle Laboratory for Cancer Research and Laboratory of Genetics, University of Wisconsin, Madison, Wisconsin 53706 Present address: Department of Pharmacology, University of Wisconsin, Madison, WI 53706.

As genetic mapping of quantitative trait loci (QTL) becomes routine, the challenge is to identify the underlying genes. This paper develops rigorous genetic tests for evaluation of candidate genes for a QTL, involving determination of allelic status in inbred strains and fine-structure genetic mapping. For the Mom1 modifier of intestinal adenomas caused by Apc(Min), these tests are used to evaluate two candidate genes: Pla2g2a, a secretory phospholipase, and Rap1GAP, a GTPase activating protein. Rap1GAP passes the first test but is excluded by a single fine-structure recombinant. Pla2g2a passes both tests and is a strong candidate for Mom1. Significantly, we also find that Apc(Min)-induced adenomas remain heterozygous for the Mom1 region, consistent with Mom1 acting outside the tumor lineage and encoding a secreted product.