As a “Star Trek” fan, the phrase “live long and prosper” resonates with David Egan. When he was born in 1977, the idea that people with Down syndrome could have long and prosperous lives was far from mainstream. But his parents saw him as an individual with his own unique strengths and weaknesses. Thanks to the support of his parents, his community and his own resourcefulness, Egan has been able to — to borrow another “Star Trek” saying — “boldly go where no one has gone before.”