Question?: Rett Syndrome Genetics

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George asks…

what is autism?

Im not sure what that is

admin answers:

Autism is a brain development disorder that impairs social interaction and communication, and causes restricted and repetitive behavior, all starting before a child is three years old. This set of signs distinguishes autism from milder autism spectrum disorders (ASD) such as Asperger syndrome.[2]

Autism has a strong genetic basis, although the genetics of autism are complex and it is unclear whether ASD is explained more by multigene interactions or by rare mutations.[3] In rare cases, autism is strongly associated with agents that cause birth defects.[4] Other proposed causes, such as childhood vaccines, are controversial and the vaccine hypotheses lack convincing scientific evidence.[5] Most recent reviews estimate a prevalence of one to two cases per 1,000 people for autism, and about six per 1,000 for ASD, with ASD averaging a 4.3:1 male-to-female ratio. The number of people known to have autism has increased dramatically since the 1980s, at least partly due to changes in diagnostic practice; the question of whether actual prevalence has increased is unresolved.[6]

Autism affects many parts of the brain; how this occurs is poorly understood. Parents usually notice signs in the first two years of their child’s life. Early behavioral or cognitive intervention can help children gain self-care, social, and communication skills. There is no cure.[7] Few children with autism live independently after reaching adulthood, but some become successful,[8] and an autistic culture has developed, with some seeking a cure and others believing that autism is a condition rather than a disorder.[9]

* 1 Classification
* 2 Characteristics
o 2.1 Social development
o 2.2 Communication
o 2.3 Repetitive behavior
o 2.4 Other symptoms
* 3 Causes
* 4 Mechanism
o 4.1 Pathophysiology
o 4.2 Neuropsychology
* 5 Screening
* 6 Diagnosis
* 7 Management
* 8 Prognosis
* 9 Epidemiology
* 10 History
* 11 References
* 12 External links


Autism is a brain development disorder that first gives signs during infancy or childhood and follows a steady course without remission or relapse.[2] Impairments result from maturation-related changes in various systems of the brain.[10] Autism is one of the five pervasive developmental disorders (PDD), which are characterized by widespread abnormalities of social interactions and communication, and severely restricted interests and highly repetitive behavior.[2]
Hans Asperger introduced the modern sense of the word autism in 1938.
Hans Asperger introduced the modern sense of the word autism in 1938.[11]

Of the other four PDD forms, Asperger syndrome is closest to autism in signs and likely causes; Rett syndrome and childhood disintegrative disorder share several signs with autism, but may have unrelated causes; PDD not otherwise specified (PDD-NOS) is diagnosed when the criteria are not met for a more specific disorder.[12] Unlike autism, Asperger’s has no substantial delay in language development.[13] The terminology of autism can be bewildering, with autism, Asperger’s and PDD-NOS often called the autism spectrum disorders (ASD)[7] or sometimes the autistic disorders,[14] whereas autism itself is often called autistic disorder, childhood autism, or infantile autism. In this article, autism refers to the classic autistic disorder, while other sources sometimes use autism or the autisms to refer to ASD,[15] or equate ASD with PDD.[16] ASD, in turn, is a subset of the broader autism phenotype (BAP), which describes individuals who may not have ASD but do have autistic-like traits, such as avoiding eye contact.[17]

The manifestations of autism cover a wide spectrum, ranging from individuals with severe impairments—who may be silent, mentally disabled, and locked into hand flapping and rocking—to less impaired individuals who may have active but distinctly odd social approaches, narrowly focused interests, and verbose, pedantic communication.[18] Sometimes the syndrome is divided into low-, medium- and high-functioning autism (LFA, MFA, and HFA), based on IQ thresholds,[19] or on how much support the individual requires in daily life; these subdivisions are not standardized and are controversial. Autism can also be divided into syndromal and non-syndromal autism, where the former is associated with severe or profound mental retardation or a congenital syndrome with physical symptoms, such as tuberous sclerosis.[20] Although individuals with Asperger’s tend to perform better cognitively than those with autism, the extent of the overlap between Asperger’s, HFA, and non-syndromal autism is unclear.[21]

Some studies have reported diagnoses of autism in children due to a loss of language or social skills after 14 months of age, as opposed to a failure to make progress. Several terms are used for this phenomenon, including regressive autism, setback autism, and developmental stagnation. The validity of this distinction remains controversial; it is possible that regressive autism is a specific subtype.[22][23][24]


Autism is distinguished by a pattern of symptoms rather than one single symptom. The main characteristics are impairments in social interaction, impairments in communication, restricted interests and repetitive behavior. Other aspects, such as atypical eating, are also common but are not essential for diagnosis.[25] Individual symptoms of autism occur in the general population and appear not to associate highly, without a sharp line separating pathological severity from common traits.[26]

Social development

People with autism have social impairments and often lack the intuition about others that many people take for granted. Noted autistic Temple Grandin described her inability to understand the social communication of neurotypicals as leaving her feeling “like an anthropologist on Mars”.[27]

Social impairments become apparent early in childhood and continue through adulthood. Autistic infants show less attention to social stimuli, smile and look at others less often, and respond less to their own name. Autistic toddlers have more striking social deviance; for example, they have less eye contact and anticipatory postures and are more likely to communicate by manipulating another person’s hand.[24] Three- to five-year-old autistic children are less likely to exhibit social understanding, approach others spontaneously, imitate and respond to emotions, communicate nonverbally, and take turns with others. However, they do form attachments to their primary caregivers.[28] They display moderately less attachment security than usual, although this feature disappears in children with higher mental development or less severe ASD.[29] Older children and adults with ASD perform worse on tests of face and emotion recognition.[30]

Contrary to common belief, autistic children do not prefer to be alone. Making and maintaining friendships often proves to be difficult for those with autism. For them, the quality of friendships, not the number of friends, predicts how lonely they are.[31]

There are many anecdotal reports, but few systematic studies, of aggression and violence in individuals with ASD. The limited data suggest that in children with mental retardation, autism is associated with aggression, destruction of property, and tantrums. Dominick et al. Interviewed the parents of 67 children with ASD and reported that about two-thirds of the children had periods of severe tantrums and about one-third had a history of aggression, with tantrums significantly more common than in children with a history of language impairment.[32]


About a third to a half of individuals with autism do not develop enough natural speech to meet their daily communication needs.[33] Differences in communication may be present from the first year of life, and may include delayed onset of babbling, unusual gestures, diminished responsiveness, and the desynchronization of vocal patterns with the caregiver. In the second and third years, autistic children have less frequent and less diverse babbling, consonants, words, and word combinations; their gestures are less often integrated with words. Autistic children are less likely to make requests or share experiences, and are more likely to simply repeat others’ words (echolalia)[23][34] or reverse pronouns.[35] Joint attention seems to be necessary for functional speech, and deficits in joint attention seem to distinguish infants with ASD:[1] for example, they may look at a pointing hand instead of the pointed-at object,[24][34] and they consistently fail to point to “comment” about or “share” an experience at age-appropriate times.[1] Autistic children may have difficulty with imaginative play and with developing symbols into language.[23][34]

In a pair of studies, high-functioning autistic children aged 8–15 performed equally well, and adults better than individually matched controls at basic language tasks involving vocabulary and spelling. Both autistic groups performed worse than controls at complex language tasks such as figurative language, comprehension and inference. As people are often sized up initially from their basic language skills, these studies suggest that people speaking to autistic individuals are more likely to overestimate what their audience comprehends.[36]

Repetitive behavior
A young boy with autism, and the precise line of toys he made
A young boy with autism, and the precise line of toys he made

Autistic individuals display many forms of repetitive or restricted behavior, which the Repetitive Behavior Scale-Revised (RBS-R)[37] categorizes as follows.

* Stereotypy is apparently purposeless movement, such as hand flapping, head rolling, or body rocking.
* Comp

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