 Shares of Generation Bio Inc., a biotech that specializes in gene therapy treatments for rare diseases, soared 23 Friday in their trading debut, after the IPO was upsized and priced at 19 a share, the high end of its price range. The company sold 10.5 million shares to raise 199.5 million. The shares are trading on Nasdaq, under the ticker symbol GBIO. J.P. Morgan, Jefferies, Cowen and Wedbush PacGrow were underwriters on the deal. Proceeds will be used to fund RD;, to develop platform technologies and for general corporate purposes. We are an innovative genetic medicines company creating a new class of gene therapy utilizing our proprietary non-viral gene therapy platform to provide durable, redosable treatments for millions of patients living with rare and prevalent diseases, the company says in its prospectus. 