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 is a term that refers to general diseases or malfunctions of the nerves. Nerves at any location in the body can be damaged from injury or disease. Neuropathy is often classified according to the types or location of nerves that are affected.