The British Dyslexia Association recently held a conference at Oxford in the UK.  What was described as  "overwhelming evidence" was presented that the majority of dyslexic individuals suffer from more than one condition. You'll hear this referred to as "comorbidity". The most common condition that frequently overlaps with dyslexia is ADHD. Other dyslexic children also suffer from various co-ordination disorders, also known as dyspraxia, and other conditions such as Asperger's Syndrome.