When peripheral neuropathy is part of an inherited syndrome (Figure 1B and C), it is typically overshadowed by the other manifestations. Nevertheless, demyelination or dysmyelination of peripheral axons is a feature of metachromatic (OMIM 250100) and globoid-cell (OMIM 245200) leukodystrophy as well as Cockayne syndrome (OMIM 216400), syndromes associated with SOX10 mutations (OMIM 602229 and OMIM 609136), congenital disorder of glycosylation type Ia (OMIM 212065), Refsum disease (OMIM 266500), congenital cataracts, facial dysmorphism, and neuropathy (OMIM 604168), and minifascicular neuropathy (OMIM 605423). Syndromes associated with axonal neuropathies are even more common. Several types of hereditary spastic paraparesis or paraplegia (SPG) have an axonal neuropathy involving both motor and sensory axons (SPG types 7, 11, 20, and 23) or just motor axons (SPG17, or Silver syndrome). An axonal neuropathy is a feature of many hereditary ataxias, including Friedrich ataxia (OMIM 229300), ataxia-oculomotor apraxia type 2 (OMIM 606002), spinocerebellar syndrome with axonal neuropathy (OMIM 607250), and spinocerebellar ataxia types 1, 2, 3, 4, 6, 7, and 25.11 The clinical phenotypes of giant axonal neuropathy, neuraxonal dystrophy, and SPG associated with peripheral axonal neuropathy are consistent with the idea that these diseases are length-dependent axonopathies of both central and peripheral nervous system neurons.