JOINT FILING AGREEMENT

Exhibit 99

JOINT FILING AGREEMENT

In accordance with Rule 13d-1(k)(1) promulgated under the Securities Exchange Act of 1934, as amended, the undersigned hereby agree to the joint filing with each other on behalf of each of them of such a statement on Schedule 13G with respect to the Ordinary Shares beneficially owned by each of them of Prosensa Holding N.V. This Joint Filing Agreement shall be included as an Exhibit to such Schedule 13G.

IN WITNESS WHEREOF, the undersigned hereby execute this Joint Filing Agreement as of the 12th day of February, 2014.

LSP Prosensa Pooling B.V.
By:		LSP III Management B.V.				By:		LSP IV Management B.V.
Title:		Managing Director				Title:		Managing Director
By:		/s/ X. Xxxxxxxxx and X.X. Xxxxxxx				By:		/s/ X. Xxxxxxxxx and R.R. Kuijten
Name:		X. Xxxxxxxxx and X.X. Xxxxxxx				Name:		X. Xxxxxxxxx and R.R. Kuijten
Title:		Managing Directors				Title:		Managing Directors
LSP III Omni Investment Coöperatief U.A.
By:		LSP III Management B.V.
Title:		Managing Director
By:		/s/ X. Xxxxxxxxx and X.X. Xxxxxxx
Name:		X. Xxxxxxxxx and R.R. Kuijten
Title:		Managing Directors
LSP III Management B.V.
By:		/s/ X. Xxxxxxxxx and X.X. Xxxxxxx
Name:		X. Xxxxxxxxx and R.R. Kuijten
Title:		Managing Directors
Coöperatief LSP IV U.A .
By:		LSP IV Management B.V.
Title:		Managing Director
By:		/s/ X. Xxxxxxxxx and X.X. Xxxxxxx
Name:		X. Xxxxxxxxx and R.R. Kuijten
Title:		Managing Directors
LSP IV Management B.V.
By:		/s/ X. Xxxxxxxxx and X.X. Xxxxxxx
Name:		X. Xxxxxxxxx and R.R. Kuijten
Title:		Managing Directors