Unexpectedly, three proteins found to be differentially abundant between 6-month-old heterozygous mutant and wild type zebrafish have causative roles in human neurodegenerative diseases: apolipoprotein Eb (encoded by the zebrafish apoeb gene, orthologous to the major human genetic risk factor for sporadic AD, APOE), superoxide dismutase (encoded by the zebrafish sod1 gene, orthologous to the human SOD1 gene mutated in familial amyotrophic lateral sclerosis), and protein DJ-1 (encoded by the zebrafish park7 gene, orthologous to the human PARK7 gene mutated in familial Parkinson’s disease). Here, APOE is linked to neurodegenerative disease.