Benitec Biopharma Ltd., of Sydney, said the FDA granted orphan designation to BB-301 for the treatment of oculopharyngeal muscular dystrophy (OPMD). BB-301 is a single vector (gene therapy construct) system that uses DNA-directed RNA interference to silence expression of the mutant gene associated with OPMD, while simultaneously adding back a copy of the normal version of the same gene to restore gene function. Human trials are set to start by the end of this year.