Lack of apoptosis in patients with progressive external ophthalmoplegia and mutated adenine nucleotide translocator-1 gene.

Adenine nucleotide translocator-1 (ANT-1), encoded by chromosome 4 (4q34-35 locus), is a component of the mitochondrial permeability transition pores that are involved in apoptotic mechanisms. We studied muscle biopsies from seven individuals with autosomal dominant progressive external ophthalmoplegia caused by ANT-1 mutations. We found no instance of terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL) positivity nor significant expression of apoptosis-related proteins. Furthermore, there was no morphological evidence of apoptosis at the ultrastructural level. Thus, degeneration of muscle in this disorder is nonapoptotic.