Rett syndrome (RTT) is a neurodevelopmental condition characterized by the loss of spoken language and hand use, coupled with the development of distinctive hand stereotypies. This disorder is seen in infancy and occurs almost exclusively in females. It is usually caused by a mutation of the MECP2 gene on the X chromosome. Rett syndrome is found in all racial and ethnic groups throughout the world. It affects one in every ten thousand live female births. Early developmental milestones appear normal, but between 6-18 months of age, there is a delay or regression in development, particularly affecting speech, hand skills and gait. A hallmark of Rett syndrome is repetitive hand movements that may become almost constant while awake. Other more common medical issues encountered include epileptic seizures, muscle stiffness, osteoporosis and scoliosis. Despite its multiple handicaps, Rett syndrome is not a degenerative disease. Many individuals with Rett syndrome live long into adulthood. There is currently no cure.