Kill them all...

Miles Cookson has been diagnosed with Huntington's disease. He is rich, is not married and doesn't have any children, except when he was young and desperately in need of money, he donated his sperm to a fertility clinic. As Huntington's is a genetic disorder, he believes his biological children are entitled to know they may have the disease. He decides to find them one by one, warn them and help them financially if needed.
Except someone else is hunting them down and making them disappear.