Expression of emerin and lamins in muscle of patients with different forms of Emery-Dreifuss muscular dystrophy

Emerin and lamins are nuclear proteins, which are missing or defective in Emery-Dreifuss muscular dystrophy (EDMD). The aim of this study was to test the expression of these proteins in skeletal muscles in the X-linked (X-EDMD) and autosomal dominant (AD-EDMD) form. The study group consisted of 11 patients with X-EDMD, 11 patients of the AD-EDMD and 20 age-matched normal subjects. Expression of emerin and lamins in muscles were analyzed by Western blotting and the immunocytochemical technique. Using the Western blotting procedure emerin was detected in traces in the X-linked form. In the majority of these cases (6/11) it was connected with a decreased concentration of lamin A, in four patients a lowered concentration of lamin C was present. Lamin B2 was either normal (8/11), or decreased (3/11). Deficit of lamin A was a characteristic feature for AD-EDMD in the majority of these cases (9/11), while in two of these patients a decrease of lamin C, in four cases a lowered level of emerin was also present. In one AD-EDMD patient of a decrease of lamin C, but normal lamin A was present. Following the immunocytochemical examination the decrease of lamin A/C in X-EDMD and of emerin in AD-EDMD was also observed. The above mentioned data demonstrated that in X-EDMD and AD-EDMD the deficit of the appropriate proteins is not restricted either to emerin or lamins. The defect is more widespread and results in disruption of several nuclear proteins. This study also indicated that for the diagnostic EDMD purposes the immunocytochemical detection of emerin/lamins has to be accomplished by quantitative immunochemical analyses of the above mentioned proteins.