PTC Therapeutics (NASDAQ:PTCT) shares soared recently after the EU issued a preliminary approval for the company's Duchenne muscular dystrophy (DMD) drug, Translarna. This caught the market by surprise, which explains the 59% gains over the course of 3 days. Is their still upside in Translarna, or would investors be better served taking a long look at one of its competitors?

The other two stocks attmepting to treat DMD are using a different approach from PTC and have had mixed results. Prosensa's (Nasdaq: RNA) drug failed a phase 3 trial and its big pharma partner walked away, while Sarepta (Nasdaq: SRPT) has promising enough mid-stage results that it is pushing for an accelerated approval from the FDA.

In this episode of The Motley Fool's health-care show Market Checkup, analysts David Williamson and Michael Douglass talk about Translarna's surprising approval and what it means for investors in PTC Therapeutics, Sarepta, and Prosensa. 

David Williamson owns shares of Merck. Michael Douglass has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.