Background N-ethyl-N-nitrosourea (ENU)-induced mouse mutagenesis is a powerful approach for the study of gene function and the generation of human disease models.Objective This study was to create the corneal morphologic change and map the mutant gene of a kind of corneal opacity in ENU mutagenesis in mouse.Methods ENU was intraperitoneally injected in forty C57BL/ 6J (B6) male mice aged 8-10 weeks old.The male mice were mated with the same strain female mice.Their progenies were screened for visible eye mutation,and the mutant mice were mated with the same strain mice to confirm the heredity of mutation phenotypes.Hematoxylin & eosin staining was used to examine the histopathological change of cornea in one mouse with ENU-induced corneal opacity.To map the mutant gene,[(B6×D2)F1 ×B6] N2 mutant mice were bred,and the genome of the N2 mice was scanned by microsatellite markers distributed equally on the mouse chromosome.The microsatellite linked to the mutant gene was determined by the log odds score.This experimental procedure was approved by Ethic Committee about Experimental Animal Care and Use of Yangzhou University.Results The founder mouse,which was the progeny of an ENU-treated B6 male mouse and an untreated B6 female mouse,had a corneal opacity phenotype.After mating the mutant with B6 mice,19 of 59 descendants appeared corneal opacity phenotype.Thickening of corneal stroma,neoangiogenesis,infiltration of inflammatory cells and proliferation of fibroblasts were exhibited in cloudy cornea in ENU-induced mutated mice under the optical microscope.After linkage analysis between microsatellite markers and the mutant gene,the mutant gene was linked to D2Mi307,which was located at 63.42 cM.Three cases of 26 N2 mice underwent recombination with the LOD 3.79.The mutant gene associated with the cornea phenotype was located on chromosome 2.Conclusions This study map the mutant gene associated with the cornea phenotype on chromosome 2.The strain might be used as a mouse model for heritable human corneal opacity.