Dystrophin Dp116: A Yet to Be Investigated Product of the Duchenne Muscular Dystrophy Gene

The Duchenne muscular dystrophy (DMD) gene is one of the largest genes in the human genome. The gene exhibits a complex arrangement of seven alternative promoters, which drive the expression of three full length and four shorter isoforms. Dp116, the second smallest product of the DMD gene, is a Schwann cell-specific isoform encoded by a transcript corresponding to DMD exons 56–79, starting from a promoter/exon S1 within intron 55. The physiological roles of Dp116 are poorly understood, because of its extensive homology with other isoforms and its expression in specific tissues. This review summarizes studies on Dp116, focusing on clinical findings and alternative activation of the upstream translation initiation codon that is predicted to produce Dp118.