Dyslexia is a learning disability, a condition that makes it difficult to learn and understand things in the same way others do. It is a very common problem and has an effect on the way our brain understands words. The most common signs of dyslexia are reading and writing problems. Estimates are that in the United States between 5 and 9% of school children have dyslexia, though estimates go as high as 50%. Some cases of Dyslexia can be more damaging, commonly caused by a tumour in the brain which can result in lower cognitive function and in many cases, death. Dyslexia tumours can appear anywhere in the brain meaning that some dyslexia is different from others, ranging from problems with letters to paralysis and often death. There are a large array of dyslexia types, the rarest being contagious dyslexia. Approximately 1 in every 1,000,000,000 (billion) person suffers from this, which is located in the lower half of the cerebellum in all cases. This is critically damaging to motor skills such as movement and speech, often leading to major paralysis if the tumour grows. 