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.
Knowledge center. Neuropathy is the term used to describe a problem with the nerves, usually the 'peripheral nerves' as opposed to the 'central nervous system' (the brain and spinal cord). Neuropathy is seen with a number of different underlying medical conditions.