Clinical Scorecard: Common MC1R Genetic Variants and the Course of Parkinson Disease
At a Glance
Category
Detail
Condition
Clinical topic addressed by the source article: Common MC1R Genetic Variants and the Course of Parkinson Disease
Key Mechanisms
Mechanisms or clinical associations described in the source article.
Target Population
Population described in the source article.
Care Setting
Longitudinal cohort research using clinical assessments and imaging; the PPMI analyses also compared baseline cerebrospinal fluid profiles and evaluated dopamine transporter SPECT.
Key Highlights
The study examined whether MC1R loss-of-function variants were associated with differences in Parkinson disease progression after onset, using PPMI and an independent replication cohort drawn from SURE-PD phase 2, SURE-PD3, and STEADY-PD III.
The primary analysis used sporadic Parkinson disease participants in PPMI; 231 were MC1R variant carriers and 152 were noncarriers.
Motor decline was assessed with MDS-UPDRS Part III over as many as 12 years of follow-up.
Secondary measures included nonmotor and cognitive assessments, cerebrospinal fluid biomarkers, and dopamine transporter SPECT.
The supplied article text describes the study rationale and methods but does not provide results.
Guideline-Based Recommendations
Diagnosis
Study classification of MC1R loss-of-function variants used coding variants with experimental evidence of reduced receptor function.
Prodromal participants were enrolled for investigator-diagnosed rapid eye movement sleep behavior disorder or hyposmia defined as a University of Pennsylvania Smell Identification Test score at or below the 15th age- and sex-adjusted percentile.
Management
Monitoring & Follow-up
Motor progression was evaluated using MDS-UPDRS Part III in off and on states.
Secondary longitudinal measures included MDS-UPDRS Parts I, II, and IV, MoCA, SCOPA-AUT, ESS, GDS, and DAT-SPECT specific binding ratio.
Risks
The article notes that associations between individual MC1R variants and Parkinson disease susceptibility have been inconsistent.
The supplied text does not report whether MC1R variants were associated with progression outcomes.
Patient & Prescribing Data
PPMI included Parkinson disease, genetic registry, and prodromal cohorts. The primary analysis cohort comprised sporadic Parkinson disease participants; participants with specified established pathogenic variants or without evidence of dopamine deficiency were excluded.
No treatment comparison or prescribing recommendation is reported in the supplied text. The source describes MC1R agonists as used clinically for rare dermatological disorders and reports neuroprotective effects in preclinical studies.
Clinical Best Practices
Interpret the findings as a longitudinal cohort investigation; the supplied text does not establish clinical recommendations.
by Jackson G. Schumacher, Xinyuan Zhang, Jian Wang, Johannes M. Dijkstra, Hirohisa Watanabe, Xiang Gao, Marianna Cortese, Eric A. Macklin, Michael A. Schwarzschild, Xiqun Chen
