An Ohio mom has revealed her 'heartbreak' after her eight-year-old son was diagnosed with a rare disease that will lead to childhood dementia. Grayson Naff was diagnosed with Batten disease last year - a group of rare genetic conditions that cause the brain to gradually shut down over five to ten years. His mother, Emily Blackburn, from Tipp City, said: 'This is what heartbreak is. The pain is beyond words. There are times I have trouble breathing through this nightmare.' Batten disease affects