We can observe a phenotype whether or not we understand the genetics behind it. In real life, there is a gene called HERC2 that works like I described, and most people with blue eyes have the broken allele of this gene.
Nerves, Neuroglia, and Ganglia. A nerve is a bundle of fibres (axons and/or dendrites) outside the CNS. Neuroglia are cells of the nervous system that help protect and support it. Ganglia are groups of nerve cell bodies lying outside the CNS.
Neuropathy means that there is a problem with the nerves. Peripheral refers to the peripheral nervous system, which is all of the nerves that branch from the central nervous system (brain and spinal cord) and travel to the feet and hands - the periphery of the body.