Mecp2 duplication was first discovered in 2005. It is rare chromosome abnormality on the long arm of the x chromosome at xq28. Although there are a couple of reported cases in girls it occurs almost exclusively in boys. This is because girls have two x chromosomes and carry the abnormality on only one so the other unaffected x chromosome usually kicks in and takes over. In most cases they are unaffected however as males only have one x chromosome they are fully affected by the abnormality.

Children with MECP2 duplication are all affected slightly differently however there are common features.

• Hypotonia (floppiness or low muscle tone).

• Absent or little speech.

• Severe learning difficulty.

• Progressive neurological conditions such a seizures and increased muscle spasticity.

• Recurrent chest infections and pneumonia which are a major cause of death with almost half affected succumbing before age 25

• Severe constipation and reflux.

• Autistic like behaviors such as hand flapping and rocking.

• Ataxia (balance and control issues)

• Teeth grinding

Children with MECP2 Duplication syndrome sometimes have facial features in common such as large ears, a flat nasal bridge, facial hypotonia may result in an inverted v shaped upper lip, microcephaly (unsually small head) however these features are so small they often look like normal children and may look just like siblings.