PLD3 and early-onset autosomal dominant Alzheimer disease: Mutations in the 5′-3′ exonucleasePLD3 gene, also known as phospholipase D3, have previously been attributedto patients with late-onset Alzheimer’s disease.36−38 Loss of function leads to increased levels of amyloid beta, whichaccumulates in the brains of patients with the disease.39