Dyslexia is a learning disability that appears to be passed on through genetics. Although somebody with this disability may have difficulty with reading, writing, listening, and/or speaking, they may be completely functional at an average or excellence level in other areas, such as being productive, having a high IQ, or possessing a high understanding of the sciences (Albert Einstein was suspected as being a dyslexic!). The only fault in their abilities is the difficulty of converting thought to words and vice versa.
Since the ability to sense our surroundings and interpret the "data" that we sense is performed by the brain, the brain certainly plays a huge role in this disability, but the exact role it plays and how it causes a person to have dyslexia is still unclear. What has been discovered is that there is a lack of symmetry in the part of the brain that is associated with language (located on the left hemisphere), and that there is less activity in these regions than those of non-dyslexic people during a reading assignment. There are many theories as to how a certain brain impairment may contribute to the characteristics of dyslexia. It may be that a pathway is interrupted from when our eyes see something to converting that "something" to a certain meaning in our brain. Another theory is that there is impairment in the cerebellum. Since the cerebellum is responsible for movement, if a pathway in the cerebellum is interrupted it may affect one's speech.
Although there are no concrete evidence as to the specific cause and source of how dyslexia comes about, the brain is certainly responsible for the symptoms that are observed. The brain is one of the most important, if not the most important, organ in the human body. It responsible for our emotions, for our actions, for our biochemical processes that allow us to live. Even a small tweak in the brain may be catastrophic in our behavior. It is no doubt that the symptoms of dyslexia, the inability to process language properly or to put thoughts to words and speak it through the mouth, may be attributed to some dysfunction in the brain.