PROXIMAL MYOTONIC MYOPATHY WITH MRI WHITE-MATTER ABNORMALITIES OF THEBRAIN

Proximal myotonic myopathy (PROMM) is an autosomal dominantly inherite d multisystemic disorder characterized by myotonia, proximal muscle we akness, and cataracts. This disorder is not linked to the gene locus o f myotonic dystrophy (DM). We describe three new families with PROMM. In all patients, CTG repeats of the DM gene in DNA from blood leukocyt es were normal. MRI of the brain revealed a consistent pattern of mark ed white matter hyperintensity on T-2-weighted images in four patients ; two additional patients had similar but mild to moderate MRI abnorma lities. The morphology of these abnormalities is unknown. Clinical sym ptoms of brain disease were not consistent and included mental changes with hypersomnia, parkinsonian features, stroke-like episodes, and se izures. The causative relationship of these clinical features with the MRI white matter abnormalities remains to be established. Our observa tions suggest that PROMM may involve the brain.