A non-proteinogenic L-alpha-amino acid that is L-alanine in which one of the methyl hydrogens is replaced by a methylamino group. A non-proteinogenic amino acid produced by cyanobacteria, it is a neurotoxin that has been postulated as a possible cause of neurodegenerative disorders of aging such as Alzheimer's disease, amyotrophic lateral sclerosis, and the amyotrophic lateral sclerosis/parkinsonism-dementia complex (ALS-PDC) syndrome of Guam.