Childhood disintegrative disorder (CDD), also known as Heller's syndrome and disintegrative psychosis, is a rare condition characterized by late onset of developmental delays—or severe and sudden reversals—in language, social function, and motor skills. Researchers have not been successful in finding a cause for the disorder. CDD has some similarity to autism, and is sometimes considered a low-functioning form of it. In May 2013, CDD, along with other sub-types of PDD (Asperger's syndrome, autism, and PDD-NOS), was fused into a single diagnostic term called "autism spectrum disorder" under the new DSM-5 manual.