“It isn’t dramatic. It’s a disease of inches.”This is how Dave Iverson describes Parkinson’s disease, the subject of his Frontline report “My father, My Brother, and Me.” The documentary uses his and his family’s experience with the disease as the backdrop for an exploration of current research aimed at understanding what causes Parkinson’s and what can be done to cure it.In the first segment, Iverson focuses on the relatively new field of Parkinson’s genetics. Just 10 years ago a genetic basis for the disease was not even suspected. But now researchers know of at least six genes that, when mutated, can greatly increase the risk for Parkinson’s.One of the most common of these mutations, located in a gene called LRRK2, has been traced to several locations, including North Africa, near the ancient site of Carthage, and Iverson’s ancestral home, the northern coast of Norway.When a researcher tells Iverson that scientists suspect that the LRRK2 mutation spread from North Africa to Norway through the Vikings, who are known to have lived in and around Carthage in about 1000 A.D. Iverson wonders to himself, “Did my own family’s Parkinson’s saga begin a thousand years ago, when some seafaring relative came calling in Carthage?”(The LRRK2 mutation is also fairly common in people with Ashkenazi Jewish heritage. Google co-founder Sergey Brin carries this mutation and talked about his experience on his blog Too. 23andMe customers can find out if they carry the mutation in the Parkinson’s disease clinical report.)Iverson’s documentary goes on to delve into the possible environmental contributors to Parkinson’s and some of the potential cures based on stem cells. He also presents the work of several scientists whose research suggests that exercise can help protect the brain from Parkinson’s. He finishes on a hopeful note, musing “we usually think of time as the enemy, but I’ve come to think that time is also an ally. Yes the disease is progressive, but so too is science.” “My Father, My Brother, and Me” airs tonight at 9 p.m. ET on PBS. Check your local listings.The full documentary, as well as bonus interviews, Dave Iverson’s blog and links to additional resources can be found here.A live chat with Iverson will take place immediately after the program airs (10 p.m. ET) and at 11 a.m. ET on Wednesday February 4th at washingtonpost.com.