Structural Variant in Mitochondrial-Associated Gene (MRPL3) Induces Adult-Onset Neurodegeneration with Memory Impairment in the Mouse.

An impediment to the development of effective therapies for neurodegenerative disease is that available animal models do not reproduce important clinical features such as adult-onset and stereotypical patterns of progression. Using in vivo magnetic resonance imaging and behavioral testing to study male and female decrepit mice, we found a stereotypical neuroanatomical pattern of progression of the lesion along the limbic system network and an associated memory impairment. Using structural variant analysis, we identified an intronic mutation in a mitochondrial-associated gene (Mrpl3) that is responsible for the decrepit phenotype. While the function of this gene is unknown, embryonic lethality in Mrpl3 knock-out mice suggests it is critical for early development. The observation that a mutation linked to energy metabolism precipitates a pattern of neurodegeneration via cell death across disparate but linked brain regions may explain how stereotyped patterns of neurodegeneration arise in humans or define a not yet identified human disease.SIGNIFICANCE The development of novel therapies for adult-onset neurodegenerative disease has been impeded by the limitations of available animal models in reproducing many of the clinical features. Here, we present a novel spontaneous mutation in a mitochondrial-associated gene in a mouse (termed decrepit) that results in adult-onset neurodegeneration with a stereotypical neuroanatomical pattern of progression and an associated memory impairment. The decrepit mouse model may represent a heretofore undiagnosed human disease and could serve as a new animal model to study neurodegenerative disease.