Citi analyst Robyn Karnauskas started BioMarin (BMRN) with a Buy rating and $98 price target.

The analyst sees approval of pegvaliase for the treatment of phenylketonuria, which has an FDA action date of February 28, 2018, as likely driving upside. BioMarin is an orphan disease company entering a period of profitability with three “controversial” programs, Karnauskas tells investors in a research note. The analyst believes pegvaliase is underappreciated by the street. Her “blue sky scenario” for BioMarin indicates fair value of $169 per share.

The shares in premarket trading are up 4% to $85.9 after the company last night said the FDA accepted for priority review the biologics license application for pegvaliase.