Four kinds of ENU-induced white spot mice and chromosome locations of the mutant genes

“Phenotype-driven” is the name for an approach used to study gene functions through mutagenesis, location and cloning of the mutant gene. In this study, 150 male C57BL/6J(B6) mice were treated with ENU and reproduced a total offspring of 3860. Of these descendants, 210 exhibited mutation phenotypes by screening, and more than 10 of them are hereditable. Four kinds of mutant mice, named Wbct, W^−1Bao, W^−2Bao, and W^−2Bao, showed dominant hereditary white spot mutation with partial albinism on their belly, distal limbs and tail terminal. To map these mutant genes, 39 microsatellites, equally distributed on the mouse genome and with difference between B6 and DBA/2J (D2), were selected to scan the genome after discrimination of the white spots in the F₂ mice (B6xD2)xD2]. It is found that, the log odds score (LODS) between W^−1Bao and D5Mitl68 is 0.56, and the LODS of W^−1Bao and D5Mit352 is 4.47. With the gradual application of microsatellites D5Mit290, D5Mit312, D5Mit308 and D5Mit356 that are close to the mutant gene, and the number of F₂ mice going up to 537, the mutant W^−1Bao is located between D5Mit356 and D5Mit308 on chromosome 5, about 42.19 cM from the centromere. In the same way, W^−2Bao and W^−3Bao are mapped nearby W^−1Bao, and Wbct is located on chromosome 1, about 41.6 cM from the centromere. After searching for the mouse genome database (MGD) and performing a one-by-one study of all genes located on chromosome subregion, it is believed that thekit gene is an excellent candidate for the white spot mutations of W^−1Bao, W^−2Bao and W^−3Bao.