Human alpha-synuclein A53T fibril, molecular model. A53T mutation is a point mutation of the alpha-synuclein protein, a 140-amino acid protein found in pre-synaptic terminals of neurons in the brain. Wild-type alpha-synuclein fibrils are known to be the primary component of Lewy bodies, which are found in the brain of Parkinson's disease patients. The A53T mutation has been shown to have faster kinetics of fibrilisation than the wild-type protein. A53T alpha-synuclein has also been linked to early on-set familial Parkinson's disease.