SAN RAFAEL, Calif. (AP) — BioMarin Pharmaceutical will pay $680 million in cash for the Dutch biotech company Prosensa in a bid to strengthen its pipeline of genetic disorder treatments.

The San Rafael, California, company also said it will make two approximately $80 million milestone payments to Prosensa shareholders if U.S. and European regulators approve the Duchenne muscular dystrophy treatment, drisapersen.

Duchenne muscular dystrophy is a fatal genetic disease that causes increasing muscle weakness and affects one of every 3,500 boys born worldwide.

BioMarin said Monday that it will pay $17.75 for each share of the drug developer, not counting the milestone payments. That represents a 55 percent premium to the U.S.-traded stock’s closing price of $11.44 on Friday.

Shares of Prosensa Holding NV soared above BioMarin’s offer price after the deal was announced, a possible sign that investors expect a higher bid. The stock rose nearly 62 percent, or $7.06, to $18.50 hours before U.S. markets opened Monday. Shares have more than doubled in price so far this year.

Shares of BioMarin Pharmaceutical Inc. have climbed 22 percent this year as of Friday’s close at $85.83.