What is dyslexia and does it have a known cause?

Symptoms: There are several types of dyslexia, but what they have in common is the difficulty in reading comprehension. With proper instruction, this can be overcome.The cause is an unknown immaturitry of brain function.

Dyslexia is the only: learning disability for which brain structure has been related to brain dysfunction. Read "Overcoming Dyslexia" by Dr. Sally Shaywitz. During functional MRI's different areas of the brains of readers vs. nonreaders were activated during a reading task. After 9 mos. of intensive multimodal reading therapy, the same areas of the brains of the non-readers were activated as those of the fluent readers