The Michael J. Fox Foundation has announced a significant breakthrough in the search for a Parkinson's biomarker, with the development of a test that can detect alpha-synuclein pathology in spinal fluid with high sensitivity and specificity. This test, known as the alpha-synuclein seed amplification assay (αSyn-SAA), has the potential to revolutionize the diagnosis and treatment of Parkinson's disease. The test has been validated in a large-scale study and is now available for diagnostic assessment. The discovery of this biomarker is expected to accelerate the development of new treatments and improve clinical trial design.