From OMIM
X-linked Lubs-type syndromic intellectual developmental disorder (MRXSL) is a neurodevelopmental disorder characterized by severely to profoundly impaired intellectual development, infantile hypotonia, mild dysmorphic features, poor speech development, autistic features, seizures, progressive spasticity, and recurrent infections. Only males are affected, although female carriers may have some mild neuropsychiatric features, such as anxiety. Submicroscopic Xq28 duplications encompassing MECP2 are considered nonrecurrent events, because the breakpoint locations and rearrangement sizes vary among affected individuals (summary by Ramocki et al., 2010).  http://www.omim.org/entry/300260

From MedlinePlus Genetics
MECP2 duplication syndrome is a condition that occurs almost exclusively in males and is characterized by moderate to severe intellectual disability. Most people with this condition also have weak muscle tone in infancy, feeding difficulties, poor or absent speech, or muscle stiffness (rigidity). Individuals with MECP2 duplication syndrome have delayed development of motor skills such as sitting and walking. About half of individuals have seizures, often of the tonic-clonic type. This type of seizure involves a loss of consciousness, muscle rigidity, and convulsions and may not respond to medication. Some affected individuals experience the loss of previously acquired skills (developmental regression). Approximately half of individuals learn to walk, and about one-third of people with this condition require assistance when walking. Many individuals with MECP2 duplication syndrome have recurrent respiratory tract infections. These respiratory infections are a major cause of death in affected individuals, with only half surviving past age 25.  https://medlineplus.gov/genetics/condition/mecp2-duplication-syndrome