Depending on the type of receptor, the result may be an excitatory or an inhibitory effect on the postsynaptic nerve cell. Dopamine has also been implicated in the intricate effects of the psychostimulating drugs associated with drug abuse. The dietary precursors of dopamine are phenylalanine and l-tyrosine. 50 percent of patients die within 3 years of the first symptoms. In general, an ataxia is an inability to coordinate muscle activity during voluntary movement.
Spinocerebellar ataxia is the most common hereditary ataxia.
The spinocerebellar degenerative disorders are a group of diseases involving neurons in several nervous system structures, including the spinal cord and cerebellum. Inherited disease genes identified by positional cloning include Duchenne muscular dystrophy and Huntington's disease. A codon repeat is a string of identical codons which if expressed produce a string of identical amino acids in a protein.