“At one end of the spectrum, you might find the severely disabled. At the other end, you might encounter an Einstein or a Steve Jobs.”
Autism Spectrum: a complex disorder in which the social brain does not develop normally. Appears early in life, before the age of three. Because autistic children are not able to develop social and communication skills spontaneously, they withdraw into an inner world and do not interact socially with others. Includes a spectrum of disorders ranging from mild to severe. (Kandel4, 32)
Characterized by impaired social interactions, communication problems, and repetitive behaviors. (NHGRIA) Developmental disability that affects social interaction, communication, and imaginative play. (Blakeslee, 211) Marked by severe difficulties in communication and forming relationships with other people, in developing language, and in using abstract concepts. (Includes) repetitive and limited patterns of behavior and obsessive resistance to tiny changes in familiar surroundings. (OxfordMed) People with autism have difficulty reading faces. When autistic people look at another person, they avoid the eyes and instead tend to look at the mouth. ‘Neurotypical people’ … look primarily at the eyes. Where a person is looking gives us important clues about what the person desires, intends or believes. (Kandel4, 35-36) An autistic person has a human mind that cannot conceive of other minds. It is called a ‘pervasive developmental disorder,’ because so many aspects of development are disturbed: “intelligence," "perception," socializing skills, "language," and "emotion." (Doidge, 74-77)
Autism was recognized as a separate disorder in the early 1940’s by two scientists who had no contact with each other— Leo Kanner and Hans Asperger. Until then, children with the disorder had been diagnosed as mental retarded or having behavioral disorders. Kanner presented a vivid picture of three important features of classic autism in childhood: (1) a strong preference for being by oneself; (2) a desire for things to be the same, not to change; and (3) islets of creative ability. (Kandel4, 40)
The exact cause of autism is not known. (NHGRI) May be related to defects in the “mirror neuron” system or the circuits (pathways) it projects to. (RamachandranTTB, 295) Genetic factors seem to be important. For example, "identical twins" are much more likely than "fraternal twins" or siblings to both have autism. (PubMedHealth2) If one (identical) twin has autism, the chances are up to 90 percent that the other twin will be autistic. No other developmental disorder (is) as high… between identical twins. (Kandel4, 45) Many genes contribute to autism risk. Two in particular, which encode the "receptor proteins" 'neuroligin' and 'neurexin,' may explain how the condition arises. Known environmental triggers include prenatal exposures to 'rubella' and the drug 'valproate.' (Lewis, 149-150) We don’t know exactly how many genes are capable of contributing to autism, but there are very likely at least fifty, and more likely hundreds. “De novo mutations” (from fathers) are now thought to contribute to at least 10% of autism cases. The number of de novo mutations increases with paternal age. The reason is sperm “precursor cells” divide every fifteen days. This continued division and copying of DNA leads to errors. Mothers do not appear to contribute to autism by means of de novo mutations because egg cells, unlike sperm, do not divide and multiply throughout life; they are all generated before a woman is born. (Kandel, 49-51) Autism is about four times more common in boys than girls. Girls with the disorder, however, tend to have more severe symptoms and greater cognitive impairment. (NIMH, 2011) Adjective - 'autistic.' Also referred to as ‘autism spectrum disorders,’ and ‘pervasive developmental disorders.’
Asperger’s Syndrome: a rare and relatively mild autistic disorder which develops in early childhood and persists in adult life. (Oxford) A type of autism in which people have normal language skills and cognitive development but have significant problems with social interaction. (RamachandranTTB, 295) Hans Asperger identified a class of children who shared several distinct behaviors: “a lack of empathy, little ability to form friendships, one-sided conversations, intense absorption in a special interest, and clumsy movements.” He also noted that these children could talk endlessly about their favorite subjects; he dubbed them ‘little professors.’ (Grandin, 15) Asperger realized that autism does not take the same form in all people with the disorder. It covers a wide spectrum, from people who are below average in some intellectual activities and have great difficulty with language, to those who are very bright and have no difficulty with language. He found that autism persists and is evident in adults as well as children. Some of (the children) Asperger saw functioned on a very high intellectual level; for example, Elfriede Jelinek, who was awarded a Nobel Prize in Literature, was a patient of Asperger’s. Until quite recently, high-functioning autistic children and adults were diagnosed as having Asperger’s syndrome. Today, Asperger’s syndrome is generally considered part of the autism spectrum. (Kandel4, 41) Editor’s note - Asperger’s Syndrome is not included in "DSM-5."
Rett Syndrome: disorder of the nervous system that leads to developmental reversals, especially in the areas of expressive language and hand use. Occurs almost always in girls. It may be misdiagnosed as autism or cerebral palsy. Studies have linked many Rett syndrome cases to a defect in a gene on the "X chromosome." Females have two X chromosomes. Even when one chromosome has this defect, the other X chromosome is normal enough for the child to survive. Males born with this defective gene do not have a second X chromosome to make up for the problem. Therefore, the defect usually results in miscarriage, stillbirth, or very early death. The condition affects about 1 out of 10,000 children. (PubMed Health) Inherited neurological developmental disorder that is associated with X-Linked inheritance. The affected female is normal until the age of 6-25 months when progressive loss of voluntary control of hand movements and communication skills; seizures; and (autistic-like-behavior) appear. (MeSH) The gene behind the disorder (‘MECP2’) is on the X-chromosome. Affects several organ systems because the gene adds "methyl groups" to other genes, silencing them. Difficult to study because nerve cells do not divide. (Lewis, 125) No Rett syndrome “risk factors” have been identified. There is no known method for preventing Rett syndrome. (WebMD) Editor’s note - Rett Syndrome is no longer considered one of the Autism Spectrum Disorders in "DSM-5."
William’s Syndrome: a syndrome caused by multiple gene deletions from a region of chromosome 7 and characterized by distinctive facial appearance (elfin facies), mild-to-moderate developmental delay, cheerfulness, cardiovascular dysfunction, and endocrine abnormalities, including precocious puberty, and hypothyroidism. (NCIt) About a decade ago, scientists discovered that we may have have differences in the structure of our “chromosomes.” We may be missing a small bit of “DNA” from a chromosome, or we may have an extra bit of DNA in chromosome. Having an extra copy of one segment of chromosome 7 puts people at much great risk of developing a disorder on the autism spectrum. (When a bit of DNA) in that same region is lost, however, the result is Willliams Syndrome— virtually the reverse of autism. Children with this genetic disorder are extremely social. They have a strong, almost irrepressible desire to speak and communicate. They are very friendly and trusting, even of strangers Whereas some children with autism have strong drawing skills, children with Williams syndrome tend to be musical. Unlike children with autism, children with Williams syndrome have good language skills and do well with face recognition. The fact that this single segment, containing about twenty-five of the twenty-one thousand or so genes in our genome, could have such a profound influence on complex social behavior is astonishing. (Kandel4, 48-49) Author’s note - see “copy number depletion” and “copy number duplication” on the page “Genetic Variation.”