Autism Spectrum Disorder

Parallel to this, the focus on genetics is Particularly convicted in twin studies, which establish a comparison between monozygotic twins that are identical and dizygotic twins, which are opposingly non-identical. This distinction can be identified in Torgersens study, which compared MZ and same sex DZ twins where one proband had an anxiety disorder, and it was discovered that such disorders were 5x more frequent in MZ twin pairs, who mutually shared identical genetics.

Monozygotic twins: Monozygotic twins are also known as identical twins. These twins start their life as one egg which is fertilized by one sperm and latter splits into two eggs much earlier in the gestational period. These are very rare and have no link to heredity. But studies reveal that only one of four conceptions of twins is identical. Therefore, it seems likely that any differences between twins will have to be caused by environment rather than by genetics.

Autism is the main form of autism spectrum disorders (ASD). Autism is a developmental disorder that is manifested in problems with communication, impairment of social functioning, and repetitive behaviours. According to the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-V), ASD diagnoses must meet four different areas of criteria. There are three symptoms of "deficits in social communication and interaction across contexts," four symptoms of "restricted, repetitive patterns of behaviour, interests, or activities," "symptoms must be present in early childhood," and the symptoms must "together limit and impair everyday functioning" (Carpenter, 2013). There are many theoretical positions on the causes of autism spectrum disorders. Some of which have been discounted by empirical studies that have been researched and performed.

Many of us have heard about Autism, also knows as Autism Spectrum Disorder (ASD). Some have a family member, a friend, or know someone who has ASD. Increasingly it is becoming a more common disability. “Autism is one of the fastest-growing developmental disorders in the U.S” (Autism Speaks). Autism has no respect for gender, race, social class and or ethnicity. “Autism is a pervasive developmental disorder that involves abnormal development and function of the brain.” (Autism Center of Excellence) People who have autism have a lot of difficulties with social skills, communication and also will develop behavior issues. These behavior problems of an individual with autism can vary at times and can go from mild to severe. According to the Autism Science Foundation it says,” Many people with the Autism Spectrum Disorder (ASD) also have unusual ways of learning, paying attention, and reacting to different sensations. The thinking and learning abilities of people with ASD can vary—from gifted to severely challenged.” The causes and symptoms, as well as the diagnosis, and the treatments of autism vary.

There are reported to be "no definitive causes of autism, research has found some common risk factors in children who have been diagnosed with this complex disorder. According to the US Centers for Disease Control and Prevention, about 1 in 150 children will have autism and that number is growing." (p.1) Research is reported to have found a causal

As Joseph (2004) pointed out, however, this is not always the case. Monozygotic twins are more likely to be treated in a similar way, encounter more similar environments, and be to be thought of as ‘the twins’ rather than two separate individuals. This, in turn, can lead to ‘identity confusion’ and so potentially a higher concordance rate amongst monozygotic twins. Therefore Joseph argues that the greater concordance rate seen in monozygotic twins than in dizygotic twins is a result of the differing attitudes and environments experienced by the two types of twins.

Autism has become an increasingly important public health concern as the number of yearly diagnoses of the disorder has increased since the late 20th century. The National Institute of Health estimates that 1 in 88 children in the United States are classified as having an Autism Spectrum Disorder (ASD) (NINDS, 2009), a genetic neurodevelopmental disorder that impairs children 's ability to learn and causes issues with social interaction and communication. Symptoms of ASD include delays in speech and language, issues with social interaction, and unusual behaviors/routines.

While there are many theories there is no single cause of autism. One theory assumes multiple factors interacting in complex ways (i.e. genes, environment and brain) can cause autism. Genetics play a role but do not explain the full picture or the recent increase in reported cases. According to Volkmar and Weisner (2009), "Identical twins have identical genes, while fraternal twins share only some genes. The implication of this finding was that there was potentially a very strong genetic contribution in autism. A number of studies have shown that this is the case. " (p. 26). There are medical conditions associated with autism which include, phenylketonuria, congenital rubella, tuberous sclerosis, and Fragile X. The strongest associations are with Fragile X, a genetic condition causing intellectual disability and tuberous sclerosis, a genetic disorder that causes tumors to form in many different organs, primarily in the brain, eyes, heart. There is no strong evidence that environmental etologies cause autism. Some researchers assume that environmental toxins can increase the rate of autism, but evidence proposed for environmental factors is based on a case by case report which is difficult to interpret (Volkmar & Weisner,

Secondary causes of autism include pre-natal care, environmental factors, chromosomal abnormalities and genetic disorders. Environmental factors most notably, are the role of vaccinations, specifically those with the preservative thimerosal (Caronna, Milunsky, & Tager-Flusberg, 2008). The most common genetic disorder associated with autism is fragile X syndrome. Scientists continue to investigate the etiology of ASD. Current research seems to support two etiologies of autism: Early Onset of Autism vs. Regressive Autism (Bristol-Power, 2006). There is optimism that specific causes and risk factors will be identified. The results of future investigations will facilitate enhanced screening, prevention, and therapy for "at risk" and autistic patients (CMN, 2010).

In a study of 44 sets of twins, there was a high concordance rate of autism and other disorders on the ASD spectrum for monozygotic twins (92%)5. This suggests that the genetic similarity between MZ twins influences their risk of expressing Autism. Dizygotic twins however, had a much lower concordance5, supporting the hypothesis that there is a correlation between genetic similarity and Autism risk. According to the study, complications during pregnancy are not likely to be the cause of autism, but simply happen more often in twin pregnancies5. The association of severe brain damage in pregnancy and Autism has not been found in singletons5. In 29 cases of twins discordant for Autism, biological hazards associated with brain damage usually affected the autistic twin. This

With the rate of autism being diagnosed on the rise, the amount of research and interest in the disorder has risen as well. Some research suggests that over the past two decades the occurrence of autism has increased from approximately 2-5 per 10,000 births to about 1-5 per 1,000 births (Acosta & Pearl, 2004; Fatemi et al., 2012). Still others report that the occurrence is as high as 1 in 150 kids (Amaral, Schumann, & Nordhal, 2008). Even though the spectrum of autistic disorders has been studied since 1943, there have still not been any consistent nor persuasive causes or markers, either biological or clinical, identified with autism and its range of disorders (Santangelo & Tsatsanis, 2005). In fact, even with all of the advancements in genetic research technology and the increasing interest in autism, researchers can still only account for approximately 5-15% of autistic cases (Rogers et al., 2013).

“Village idiot”, “court jester”, “witch”… could these be the original names for Autism Spectrum Disorder of recent history? It has been suggested that ASD stems from an aggregate effect of many damaged essential genes that "work" together during the early stages of development in the womb, as soon as eight weeks after conception.19 The prevailing theory for autism is that it is a polygenic or multi-factorial genetic disorder and presumes that there are multiple genes and multiple environmental forces that interact in some complex way to ultimately create the problem of autism.20 Research has shown that over the last decade that while diagnosis has increased over time, the actual percentage prevalence of autism has not risen.10

Autism affects every 1 in 68 children in America, autism is a mental condition, present from early childhood, characterized by difficulty in communicating and forming relationships with other people and in using language and abstract concepts. What causes autism? A short while ago, the answer to this question would have been “we have no clue.” Research is now bringing us the answers. First, we now know that there is no one cause of autism just as there is no one type of autism. In the last five years, scientists have identified a number of rare gene changes, or mutations, associated with autism. There has been more than a hundred autism risk genes identified. In around 15 percent of cases, a specific genetic cause of a person’s autism can be identified. In the presence of a genetic bias to autism, a number of nongenetic, or environmental, influence further increase a child’s risk. The coherent evidence of these environmental risk factors includes events before and during birth. They include progressive parental age at time of conception, maternal illness during pregnancy, extreme prematurity and highly low birth weight and certain difficulties during birth, especially those involving periods of oxygen deprivation to the baby’s brain. Mothers threatened by high levels of pesticides and air pollution could also be at higher risk of having a child with Autism Spectrum Disorder. A small but growing body of research

Autism is known as a profound neural development disorder marked by an inability to communicate and interact with others. In many families, there appears to be a pattern of autism or related disabilities, further supporting the theory that the disorder has a genetic basis. (Autism and Neurodevelopment) While no one gene has been identified as causing autism, researchers are searching for irregular segments of genetic code that children with autism may have inherited. Autism symptoms and their severity vary widely across these three core areas. (After the Diagnosis) Together, they may result in relatively mild challenges for someone on the high functioning end of the autism spectrum. While

A strength of twin studies is that they are an example of a natural-occurring variable: MZ twins share 100% of their genes, whereas DZ twins share about 50%. As the researcher doesn’t manipulate the variables themselves, the risk of researcher bias is