PROTEOLIPID PROTEIN IS NECESSARY IN PERIPHERAL AS WELL AS CENTRAL MYELIN

Alternative products of the proteolipid protein gene (PLP), proteolipi d protein (PLP) and DM20, are major components of compact myelin in th e central nervous system, but quantitatively minor constituents of Sch wann cells, A family with a null allele of PLP has a less severe CNS p henotype than those with other types of PLP mutations. Moreover, indiv iduals with PLP null mutations have a demyelinating peripheral neuropa thy, not seen with other PLP mutations of humans or animals. Direct an alysis of normal peripheral nerve demonstrates that PLP is localized t o compact myelin. This and the clinical and pathologic observations of the PLP null phenotype indicate that PLP/DM20 is necessary for proper myelin function both in the central and peripheral nervous systems.