STAMFORD, Conn.--(BUSINESS WIRE)--Two important management changes have been announced at Gen Re’s Life/Health North America reinsurance unit. Steve Mannik, CEO and President of General Re Life Corporation, will retire in the first quarter of 2016. Steve joined Gen Re in 2007, after a career that included 15 years at Manulife in Canada and 11 years as a Principal at Towers Perrin. Vincent DeMarco, who currently serves as Corporate Actuary and Head of Operations, will assume the role of CEO upon