Which of the following condition is seen only in females?

RETT SYNDROME: This is a hereditary form of mental retardation, but one that affects girls. The responsible spontaneous mutation has been shown to relate to a defect at chromosomal site Xq28, making it one of the X-linked mental retardations. A fatal outcome in boys because of a severe neonatal encephalopathy explains the expression of the disease only in girls, who are mosaics for the mutation. The syndrome is usually marked by withdrawn behavior that simulates autism, dementia, ataxia, loss of purposeful hand movements, and respiratory irregularities. Ref: Ropper A.H., Samuels M.A. (2009). Chapter 38. Developmental Diseases of the Nervous System. In A.H. Ropper, M.A. Samuels (Eds), Adams and Victor's Principles of Neurology, 9e.