Huperzine A is an alkaloid extracted from the Chinese moss Huperzia serrata, a natural inhibitor of acetylcholinesterase (AChE) and, therefore, can be used to treat different types of neurodegenerative disorders such as AD and even other problems including bruises, strains, swelling, rheumatism, schizophrenia, myasthenia gravis, and fever [127,128]. The gene discussed is ACHE; the disease is Alzheimer disease.