A mutation, c.1370A > T was found in exon 8 in family 4, which caused a glutamate substitution for valine at nucleotide 457 (E457V) in the tail domain. Analysis of nucleotide sequences of the desmin gene in family 5 revealed a c.1064G > C mutation in exon 5. This mutation resulted in a replacement of arginine with proline (R355P) in the helix 2B domain. In sporadic case 1, a c.338–339delA_G deletion mutation was identified in exon 1. This mutation caused a truncated protein at codon 115 (Q113fsX115) in the helix 1A domain. In sporadic case 2, a c.1333A > G

mutation in exon 8 resulted in a replacement BMS-777607 of threonine with alanine (T445A) in the tail domain. The affected members from different families had the same mutation as the respective Paclitaxel chemical structure index case, but these mutations did not appear in unaffected family members and in 100 control samples. The analysis provides strong evidence that the above described mutations are responsible for the disease and not a coincidental polymorphism. First, we confirmed that a vector containing wild-type desmin produced functional desmin protein capable of building a cytoplasmic network in C2C12 (Figure 5A) and SW13 (Figure 5B) cells. Then we investigated the ability of these disease-associated mutations

(S12F, L274P, L274R, R355P, T445A, E457V and Q113fsX115) to form extended filamentous networks in C2C12 and SW13 cells. Immunofluorescence analysis of the SW13 cells transfected with mutant vectors showed completely disorganized coarse aggregates and clumps scattered throughout the cytoplasm (Figure 5D,F,H,J,L,P). The C2C12 cells transfected with

mutant desmin revealed a disturbed endogenous intermediate filament structure and multiple desmin-positive clumps or abnormal solid large aggregates (Figure 5C,E,G,I,K,O). However, the E457V mutant in the tail domain did not form a cytoplasmic network like the wild-type desmin in the C2C12 and SW13 cells, but it did not cause obvious desmin aggregation (Figure 5M,N). We have identified five novel mis-sense mutations and one novel deletion mutation distributed along the desmin gene in five unrelated Chinese families and two sporadic cases with cardiac and skeletal myopathy. Prominent cardiac disorders were the major clinical characteristics in this cohort these of patients and other reported Asian patients [20–22]. The prevalence was more than 95% in our patients, but only 60% [3] to 70% [12] in Caucasian patients. Although dilated or restrictive cardiomyopathy has been considered as the most common forms of cardiac abnormalities in desminopathy patients [12], the present observations suggest that various forms of conduction block are most prominent in Chinese desminopathy patients. Kostera-Pruszczyk et al. summarized that all 47 patients examined by echocardiography in a cohort of 92 cases with desminopathy exhibited structural cardiomyopathy [12], while only six out of 25 patients presented with cardiomyopathy in our study.