_:vb50941271 . _:vb50941271 "url:http://ghr.nlm.nih.gov/condition/kleefstra-syndrome"^^ . _:vb50941271 "A syndrome that is characterized by developmental delay and intellectual disability, severely limited or absent speech, and weak muscle tone."^^ . _:vb50941271 . _:vb50941271 . _:vb50941271 .