A muscle biopsy from an Emery-Dreifuss muscular dystrophy (EMDM) patient showed complete absence of emerin by both Western blotting and immunohistochemistry, suggesting a simple diagnostic antibody test for EDMD families.
We propose immunocytochemical evaluation of emerin expression in skin biopsies as a sensitive and more convenient tool for diagnosing X-linked EDMD and, in particular, for distinguishing it from the autosomal dominant form.
Expression and subcellular distribution of emerin were studied in lymphoblastoid cell lines established from four patients with Emery-Dreifuss muscular dystrophy containing different mutations in the emerin gene.
To determine if any of the patients with RSS had mutations of the emerin gene (responsible gene for X-linked EDMD or emerinopathy), we screened the patients for mutations.
Western blot and immunohistochemistry show an absence of emerin in muscle and skin tissues and oral exfoliating cells in male patients with X-EDMD, and a reduction of the protein content with a mosaic expression pattern in female carriers.
Direct sequencing of the emerin gene in 22 families with Emery-Dreifuss muscular dystrophy (EMD) revealed mutations in 21 (95%), confirming that emerin mutations can be identified in the majority of families with X-linked EMD.
These include the mislocalization of emerin, an inner nuclear membrane protein, defects in which are implicated in Emery-Dreifuss muscular dystrophy (EDMD), one of the three major X-linked dystrophies.
The gene, STA at Xq28, for the commoner X-linked EDMD encodes a 34 kD nuclear membrane protein designated 'emerin', and in almost all cases on immunostaining is absent in muscle, skin fibroblasts, leucocytes and even exfoliative buccal cells, and a mosaic pattern in female carriers.
We report on a patient with the typical clinical findings of Emery-Dreifuss muscular dystrophy due to a mutation in the emerin gene that should have produced a higher molecular weight protein.
Genetic studies have now shown that people with mutations in either lamins A/C or emerin, a nuclear membrane protein, develop Emery-Dreifuss muscular dystrophy.
In addition, we have ruled out the Emery-Dreifuss muscular dystrophy to be allelic with XMEA by direct sequencing of the emerin gene in three of our families.
Emery-Dreifuss Muscular Dystrophy (EMD or EDMD) is a rare X-linked recessive disorder, characterized by progressive muscle wasting and weakness, contractures, and cardiomyopathy, manifesting as heart block.
Mutations in the STA gene, encoding the nuclear envelope protein emerin, are responsible for X-linked EDMD, while mutations in the LMNA gene encoding lamins A and C by alternative splicing have been found in patients with autosomal dominant, autosomal recessive, and sporadic forms of EDMD.