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Updated: Aug 26, 2026

Rating L-DOPA-Induced Dyskinesias in the Unilaterally 6-OHDA-Lesioned Rat Model of Parkinson's Disease
Published on: October 4, 2021
Levodopa-responsive aromatic L-amino acid decarboxylase deficiency
Yuh Terng Chang1, Radhakant Sharma, J Lawrence Marsh
1Kimberly H. Courtwright and Joseph W. Summers Institute of Metabolic Disease, Baylor University Medical Center, 3812 Elm Street, Dallas, TX 75226, USA.
Abstract:
We report three siblings, who were treated empirically with levodopa combined with carbidopa. There was an immediate therapeutic response. Biochemical investigation surprisingly showed the clinical phenotype to be caused by aromatic L-amino acid decarboxylase deficiency. Molecular characterization showed a homozygous point mutation (c.387 G-->A) in exon 3. Kinetic studies showed the mutation to decrease the binding affinity for the substrate. This, combined with structural modeling suggesting alteration of active site configuration, provided an explanation for the therapeutic response to levodopa.
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