** Gene editing firm Intellia Therapeutics' shares fall 18% to $16.38

** Company says its experimental gene therapy to treat a rare disorder called hereditary angioedema $(HAE)$ helped reduce monthly swelling attacks by up to 81% vs placebo in a mid-stage study

** HAE is characterized by unpredictable and frequent severe swelling of the skin, gastrointestinal tract, upper respiratory system, face and throat

** "We expect investors will view the ~75-80% reduction in HAE attacks as less than impressive in the context of the potential risks of in vivo gene editing and the competitive landscape in this indication" - brokerage Baird

** HAE treatments in the U.S. that are currently approved include drugs made by Takeda Pharmaceuticals and BioCryst Pharmaceuticals

** Including session moves, Intellia shares down ~46% YTD

(Reporting by Mariam Sunny in Bengaluru)

((Mariam.ESunny@thomsonreuters.com))