Melanin has many biological functions, including colouring the skin and hairs or feathers, strengthening plant cell walls and insect cuticle, absorbing light (and so providing photoreceptor shieldlng, thermoregulation, photoprotectlon), and it is an important free radical sink.
Medical Definition of autistic disorder. : autism Autistic disorder is classic autism, one of the more severe disorders on the spectrum. Persons with autistic disorder have substantial impairment in social skills, verbal communication, and cognitive and behavioral flexibility.âIsabelle Rapin , The New England Journal of Medicine, 1 Aug. 2002.
Autism spectrum disorder (ASD) is a physical condition linked to abnormal biology and chemistry in the brain. The exact causes of these abnormalities are not known. There is likely a combination of factors that lead to ASD. It may run in some families, and research shows that a number of genes may be involved.