Pheomelanin, Eumelanin, and Neuromelanin: A Metal-Linked Hypothesis for Parkinson's Risk in Redheads

This paper bridged melanin biochemistry, metal chelation chemistry, and Parkinson's neuropathology — three fields that had never been connected through a single mechanistic framework. It explains *why* MC1R variants increase PD risk by identifying the differential metal-binding capacity of pheomelanin versus eumelanin in neuromelanin as the mechanistic linchpin. This reframed Parkinson's susceptibility in redheads from an unexplained epidemiological association into a metal-dependent biochemical vulnerability, opening an entirely new axis of investigation for WikiBiome's neurodegenerative disease signatures.