NONSENSE MUTATION IN EXON-3 OF THE PROTEOLIPID PROTEIN GENE (PLP) IN A FAMILY WITH AN UNUSUAL FORM OF PELIZAEUS-MERZBACHER-DISEASE

Fire report a G-->A transition at nucleotide 431 of the proteolipid pr otein gene (PLP) results in a nonsense codon in a family with an unusu al form of Pelizaeus-Merzbacher disease (PMD). The mutation, which cre ates a second AluI restriction site, results in a nonsense mutation in PLP, The clinical picture resembles somewhat that of X-linked spastic paraplegia (SPG), It differs from this and both the classical and con natal forms of PMD in that it is relatively mild in form, onset is del ayed beyond age 2 years, nystagmus is absent, tremors are prominent, m ental retardation is not severe, some patients show dementia or person ality disorders, the disease is progressive rather than static in some , and several females show signs of disease. The nonsense mutation, wh ich is in exon 3B, should block the synthesis of normal PLP but spare DM20, the isoform whose persistence has been associated with mild form s of PLP-associated disease in both humans and mice. (C) 1997 Wiley-Li ss, Inc.