A new mouse model for infantile neuroaxonal dystrophy, inad mouse, maps to mouse chromosome 1.

Infantile neuroaxonal dystrophy (INAD) is a rare autosomal recessive hereditary neurodegenerative disease of humans. So far, no responsible gene has been cloned or mapped to any chromosome. For chromosome mapping and positional cloning of the responsible gene, establishment of an animal model would be useful. Here we describe a new mouse model for INAD, named inad mouse. In this mouse, the phenotype is inherited in an autosomal recessive manner, symptoms occur in the infantile period, and the mouse dies before sexual maturity. Axonal dystrophic change appearing as spheroid bodies in central and peripheral nervous system was observed. These features more closely resembled human INAD than did those of the gad mouse, the traditional mouse model for INAD. Linkage analysis linked the inad gene to mouse Chromosome 1, with the highest LOD score (=128.6) at the D1Mit45 marker, and haplotype study localized the inad gene to a 7.5-Mb region between D1Mit84 and D1Mit25. In this linkage area some 60 genes exist: Mutation of one of these 60 genes is likely responsible for the inad mouse phenotype. Our preliminary mutation analysis in 15 genes examining the nucleotide sequence of exons of these genes did not find any sequence difference between inad mouse and C57BL/6 mouse.