Genotypes and Phenotypes of distal myopathy

Introduction: In the past, distal myopathy was clinically characterized by the type of the distal weakness and its beginning, the creatin kinase activity, the histopathology and genetic aspects.

In some cases, the etiologic genetic defect is already known. In this case 26 patients with distal myopathy were analysed. 10 patients (38%) were categorised in the common forms, 16 patients couldn't be classified.

Results: For ten patients we found the genetic cause. A dysferlin gene mutation was found for three patients with Miyoshi phenotype. Two of five patients with phenotype of Marksberry-Griggs myopathy showed the ZASP-mutation. The Matrin-3 mutation was found in one patient with phenotype of Welander myopathy. Four of the patients without the classical phenotype were categorised with the help of molecular analyses: FSHD (n=2), filaminopathy (n=1) and centronuclear myopathy (n=1). For three of five patients with phenotypical Marksberry-Griggs myopathy, no genetic defects could be detected. Additionally, for one patient with phenotypical Welander myopathy no underlying genetic defect was detectable.

Conclusion: In this case has been shown that distal myopathy is a heterogeneous group of disorder. The phenotype of Marksberry-Griggs myopathy is determined not only by the ZASP-mutation. On the other hand, the Miyoshi myopathy shows a high correlation between phenotype and genotype. This case was the first description of Welander phenotype with Matrin-3 mutation. Some different kinds of myopathy can turn out as distal myopathy.