Evan Clarkson (7) who has Angelman Syndrome, which used to be known as Happy Puppet Syndrome, with his mum Kerry at home in Melton Mobray, Leicestershire. See NTI story NTISMILE. A seven-year-old boy suffers from a rare genetic condition which means he cannot stop smiling. Evan Clarkson was born with Angelman syndrome – a chromosome disorder which causes severe learning difficulties – and puts a permanent smile on his face. Sufferers present a happy demeanour, so are often smiling or laughing, and tend to be easily excited. The rare condition affects between one in 15,000 to 20,000 babies born each year.