A new documentary, The Lion’s Mouth Opens, poignantly captures the precarious journey into genetic self-knowledge by Marianna Palka, a 33-year-old filmmaker-actress. She has decided to test for Huntington’s disease (HD), which has been referred to as the “devil of all diseases.” Watching a special preview of this Academy Award-shortlisted film at a meeting of leading HD scientists in February prompted me to relive my family’s struggles with HD, which destroys the brain. During the screening, I cried uncontrollably for a good while. I found consolation in a hug and encouraging words from Marianna. Directed by Lucy Walker, the film explores a harrowing predicament: Researchers have developed a test for HD, but have not yet found a way to halt the progression of