(HealthDay News) – Variants of the alpha-synuclein gene (SNCA) are associated with a higher risk of a more rapid decline in motor function in patients with Parkinson’s disease, according to a study published online May 15 in PLoS One.

Beate Ritz, MD, PhD, from the University of California Los Angeles, and colleagues examined whether genetic variants of the SNCA gene, a well-known risk factor for Parkinson’s disease, were associated with motor function decline (as assessed by the Unified Parkinson’s Disease Rating Scale) in 233 patients with Parkinson’s disease who had been diagnosed less than three years earlier.

Over an average follow-up of 5.1 years, the researchers found a higher risk of a faster decline in motor function in patients carrying the REP1 263bp promoter variant (odds ratio, 4.03). The G-allele for rs356165 also contributed to increased risk of faster decline (odds ratio, 1.66). There was a stronger trend in decline in motor function when both variants were present (P for trend=0.002).

“Our population-based study has demonstrated that SNCA variants are strong predictors of faster motor decline in idiopathic Parkinson’s disease,” Ritz and colleagues conclude. “This is the first study to link SNCA to motor symptom decline in a longitudinal progression study.”

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