Drug developer Suma Krishnan was 51 when she had the idea for a topical gene therapy to treat a rare and terrible skin disorder, called dystrophic epidermolysis bullosa, in which the skin becomes as fragile as butterfly wings. It was a risky move, as was her decision with her husband and cofounder Krish Krishnan to shun VC funding for their startup Krystal Biotech. Today, Pittsburgh-based Krystal, founded in 2016, is publicly traded, with a market cap of $4.1 billion, one FDA-approved therapy