[Clinical polymorphism, genetic heterogeneity and primary myopathy pathogenesis problems].
The peculiarities of clinic picture of primary myopathies with general gene defects, in particular differences in disease debut, dystrophy severity and degree of diverse muscle group's involvement in the dystrophic process, were analyzed. An attention was drawn specially to the cases of similar and identical mutations, including family cases, which gave rise to dramatically different pathological phenotypes. This information, along with the Becker muscular dystrophy cases (with deletions of DMD gene), describing the patients, aged 55 to 60 years, who maintained a certain movement activity, allow to revise an absolutely severe prognosis of primary myopathies and to stimulate primary myopathy pathogenesis studies. Hypothesis of "second" factors in primary myopathy's pathogenesis is discussed.