Functional annotation of mammalian genomic DNA sequence by chemical mutagenesis: A fine-structure genetic mutation map of a 1- to 2-cM segment of mouse chromosome 7 corresponding to human chromosome 11p14-p15

Eleven independent, recessive, N-ethyl-N-nitrosourea-induced mutations that map to a ≈1- to 2-cM region of mouse chromosome (Chr) 7 homologous to human Chr 11p14-p15 were recovered from a screen of 1,218 gametes. These mutations were initially identified in a hemizygous state opposite a large p-locus deletion and subsequently were mapped to finer genomic intervals by crosses to a panel of smaller p deletions. The 11 mutations also were classified into seven complementation groups by pairwise crosses. Four complementation groups were defined by seven prenatally lethal mutations, including a group (l7R3) comprised of two alleles of obvious differing severity. Two allelic mutations (at the psrt locus) result in a severe seizure and runting syndrome, but one mutation (at the fit2 locus) results in a more benign runting phenotype. This experiment has added seven loci, defined by phenotypes of presumed point mutations, to the genetic map of a small (1–2 cM) region of mouse Chr 7 and will facilitate the task of functional annotation of DNA sequence and transcription maps both in the mouse and the corresponding human 11p14-p15 homology region.