In addition, tyrosine metabolism pathways and monoamine oxidase-a (MAO-A) deficiency pathways were enriched in APPDup neurons (Fig. 2C, D)—consistent with findings that serum tyrosine is decreased in AD [29], and that MAO-A catalyzes the cleavage of APP into amyloid species [30]. The gene discussed is MAOA; the disease is Alzheimer disease.