Proximal myotonic myopathy: Clinical, electrophysiological and pathological findings in a family

Proximal myotonic myopathy (PROMM) is an autosomal dominant muscle disorder characterized by proximal weakness, myotonia, muscle pain and cataract. It resembles Steinert myotonic dystrophy (MD), but weakness is proximal, with out facial muscle involvement, and the chromosome 19 CTG trinucleotide repe at expansion characteristic of MD is not present. We describe a further fam ily with PROMM, Affected members complained of weakness of lower limbs or o f myotonia, EMG revealed diffuse myotonic discharges. Muscle histology show ed dystrophic abnormalities. The PROMM phenotype varies, even in the same p edigree, and may mimic MD or limb-girdle muscle dystrophy, EMG is particula rly useful, since it may disclose myotonic discharges even in the absence o f overt myotonia, Thus far it is not known whether PROMM is a single entity , or if it represents a heterogeneous group of disorders. This question wil l probably soon be settled through genetic analysis. Copyright (C) 2000 S. Karger AG. Basel.