Autism spectrum disorder
Fifth revision of the American Psychiatric Association's "Diagnostic and Statistical Manual of Mental Disorders 5th edition" (DSM-5) folded the following diagnoses into one, single category called "autism spectrum" or "autistic spectrum" (Spectrum Disorder Fact Sheet):
- Asperger syndrome
- pervasive developmental disorder not otherwise specified
- childhood disintegrative disorder
- Rett syndrome
There has doubtlessly been difficulty and variation in diagnosis between many of them, such as hgh functional autism or Asperger's syndrome because many of the symptoms between the former diagnosis were similar, and there was variation in symptoms even within them. GWAS studies so far have usually focused on one of the previous diagnostic categories, although diagnostic difficulties often make it unclear just which subset a study applies to. The genetic basis of Rett syndrome for example are quite well understood and different from the rest [PMID 10508514] so the combined diagnosis is less useful for genetic association.