(RNA) to Present at the 66th Annual American Academy of Neurology

Leiden, The Netherlands, April 28, 2014  — Prosensa Holding N.V. (NASDAQ: RNA) the Dutch biopharmaceutical company focusing on rare diseases with a high unmet medical need, today announced that it will present at the following US conferences:

▪66^th American Academy of Neurology (AAN) Annual Meeting, Philadelphia, PA

Poster presentation: Emerging Science Session: 6:15pm EDT on Wednesday, April 30, 2014

Drisapersen treatment for Duchenne muscular dystrophy: results of a 96-week follow-up of an open-label extension study following two placebo-controlled trials

Presenter: Dr. Nathalie Goemans

The poster includes results up to Week 48 from the second open-label extension study of drisapersen treatment in boys with DMD (DEMAND IV/DMD114349), who had previously completed a 48-week, double-blind, placebo-controlled treatment phase in one of two Phase II feeder studies (DEMAND II/DMD114117 and DEMAND III/DMD114044).

Breakfast Briefing (by invitation only): 7:30 -9:00am EDT on Thursday, May 1, 2014

Corporate Update: Hans Schikan, CEO & Giles Campion, CMO

Poster Presentation: Dr. Nathalie Goemans

Q&A: Prosensa Management, Dr. Nathalie Goemans (live) and Dr. Craig McDonald (by phone)

Dr. Goemans is a pediatrician, child neurologist and Head of the Neuromuscular Reference Center for Children at the University Hospitals Leuven (UHL). She is actively involved in the development of protocols for international multicentre trials and is an investigator in clinical trials in Duchenne Muscular Dystrophy (DMD).

Dr. McDonald is a Professor and Chair of Physical Medicine and Rehabilitation and a Professor of Pediatrics at the University of California Davis School of Medicine. He is an internationally recognized expert in the clinical management and rehabilitation of neuromuscular diseases including muscular dystrophies and the development of novel outcome measures for clinical trials.

▪39^th Annual Deutsche Bank Health Care Conference, Boston, MA

Fireside Chat: 2:10pm EDT on Wednesday, May 7, 2014; Berndt Modig, CFO

Live webcasts of Prosensa’s presentations at the AAN Breakfast Briefing and the Deutsche Bank Health Care Conference will be accessible through the Investors & Media section of the corporate website at http://ir.prosensa.eu/events.cfm and will be archived for 90 days.

Notes to editors

About Prosensa Holding N.V.

Prosensa (NASDAQ: RNA) is a Dutch biotechnology company engaged in the discovery and development of RNA-modulating therapeutics for the treatment of genetic disorders. Its primary focus is on rare neuromuscular and neurodegenerative disorders with a large unmet medical need, including Duchenne muscular dystrophy (DMD), myotonic dystrophy and Huntington’s disease.

Prosensa’s current portfolio includes six compounds for the treatment of DMD, all of which have received orphan drug status in the United States and the European Union. The compounds use an innovative technique called exon-skipping to provide a personalized medicine approach to treat different populations of DMD patients. www.prosensa.com

CONTACT: Prosensa Holding N.V.
         Celia Economides, Senior Director IR & Corporate Communications
         Phone: +1 917 941 9059
         Email: c.economides@prosensa.nl