I am a father, grandfather and author of, "Courtney's Story," a compelling true story which chronicles my daughter Courtney's personal battle with a rare viral disease called PML_ Progressive Multifocal-Leuko-encepha-lapathy which affects parts of the brain in patients with certain types of cancers and some HIV patients. The disease itself is caused from a virusleft behind as a result of the Chickenpox. Anyone who has a weakened or compromised immune system is highly susceptible to this elusive disease!