The present invention describes the identification, isolation, cloning, and determination of the Alzheimer Related Membrane Protein (ARMP) gene on chromosome 14 and a related gene, E5-1, on chromosome 1. Normal and mutant copies of both genes are presented. Transcripts and products of these genes are useful in detecting and diagnosing Alzheimer's disease, developing therapeutics for treatment of Alzheimer's disease, as well as the isolation and manufacture of the protein and the construction of transgenic animals expressing the mutant genes.