Rett Syndrome is a rare, non-inherited genetic neurological disorder that occurs in mainly girls. Girls with Rett Syndrome develop normally and show no signs until 6 to 18 months of age. Rett Syndrome does affect boys, as they have one X chromosome, but due to the mutation being only on the x chromosome there are devastating affects. Rett Syndrome affects girls differently due to the fact that they have 2 x chromosomes.  Rett Syndrome affects 1 in every 10,000 girls and there is a girl born with Rett Syndrome every 90 minutes. Each girl has a classic hand movement: hand mouthing, constant clapping or hand wringing. 99% of girls are non-verbal, but have shown to be very intelligent once taught their own form of communication.