Autism spectrum disorder is a group of very complex neurodevelopment disorders. It is characterized by patterns of difficulties in social interaction and communication as well as behavior. Its symptoms appear early in childhood thus affecting the daily functioning of the child. Some of the factors implicated in the causation of the disorder include mutations, genetic factors, deletions and copy number variants (National Institute of Mental Health, 2016). However, these factors account for a very small portion of the cases.  Cases of Autism spectrum disorder vary from mild to profound.

Landrigan in his study about the environmental contribution to the causes of autism claims that 50 percent of the autistic children have an intellectual disability while others have abnormally increased brain size. In addition, a third of them had at least two epileptic seizures by the time they attain adolescent while about half of the children have severely impaired speech. Some of the children especially those with Asperger’s syndrome have high developed intellectual skills (National Institute of Neurological Disorders and Stroke, 2016). Due to the heterogeneity, the term Autism spectrum disorder (ASD) came into use. ASD is a combination of autistic disorder, pervasive developmental disorder and Asperger’s syndrome.

Leo Kanner (1943) was the first person to describe a group of individual specifically children with the common behavior characteristics in which included social detachment, stereotypical behavior and communication deficits. These symptoms later came to be known as infantile autism. Though the AD diagnostic criteria have been amended since that year, Kanner’s symptoms remain consistent with the current definition of ASD (Worley & Matson, 2012).Initially; there was confusion about the disorder and its accurate diagnosing. The confusion stemmed from the term autism as labeled by Kanner. Eugene Bleuler (1913) was the first to use the term autism to describe the symptom exhibited by individuals diagnosed with schizophrenia. So when Kanner used the same term to describe his symptoms, it raised some confusion.

Symptoms of ASD vary from one person to the other depending on the severity of the disorder. For young children with less debilitating handicaps or mild ASD, the symptoms may be unrecognized. In adults, the diagnosis is hard to make since the symptoms may overlap with symptoms of other mental disorders such as schizophrenia. Identifying the right diagnosis is significant in helping the patient get the right treatment and help. Diagnosing depends largely on the behavior of the child. Two main types of behavior exist which are repetitive behaviors and interaction behaviors (Chaste & Leboyer, 2012). People with ASD can also have other difficulties including sensitiveness to light, noise, temperature, and clothing. Incidences of sleep problems, irritability, and digestion problems have also been reported.

People with ASD vary widely in abilities in language. These abilities range from easy language to absent speech. In addition, they also vary in cognitive development and profound intellectual disability. Individuals may also showcase of medical comorbidities such as physical anomalies and epilepsy (Chaste & Leboyer, 2012). There is an agreement among researchers that the mode of autism inheritance is not Mendelian in most of the cases.  Several studies had favored polygenic model. It is, therefore, the initial strategy used to unravel the genetic factors which increasing autism risk. Considering the individual approach which has been used in mental retardation, the search for a rare mutation was used giving a new hypothesis for the mechanism involved.

Currently, the prevalence of autism is reported to be 16 per 1000 though this rate increases to 63 per 1000 when all kind of autism spectrum disorders are included (Szatmari, 2003). Along with the changes in classification is a greater understanding of the causes of autism though the picture of the surge of biochemical and structural events that terminate in the disorder is still not clear. However, the world has developed from the era where the blame fell on mothers who it was claimed were indifferent and cold to their children. There are non-specific signs that Autism is a neuropsychiatric disorder which include epilepsy, obstetric complications, Developmental delay, an unequal sex ratio, dysmorphic features and extremes of head size.

The discovery that genetics have a key role in the cause of autism changed its understanding. In 1977, the first twin study in autism was published. The study had been done by Folstein and Rutter, and they concluded that the occurrence rate in identical twins was higher than the rate in non-identical twins. Much research has been done on this finding, and it has been proven to be true (Szatmari, 2003). The genetics involved in the disorder are complex in that the transmission does not follow any pattern recognizable. Modeling studies have shown that several genes in contact probably account for the genetic complexity essential to the disorder.

Studies have suggested that autism is heritable though there is no explanation of the heritability basis.  A study was done by Timothy et Al.., (2013) on a family with three affected children and two unaffected children revealed that “the mutation was heterozygous in both parents, homozygous in all affected children, and absent or heterozygous in the two unaffected children.”

Familiar factors and genetics are involved in the causation of autism. Autism has commonly been observed in twin and sib pairs. Occurrence in monozygotic twins is reported to be as high as 70 percent. For families with autistic children, members may contain autistic traits such as repetitive behavior and social isolation. Autism occurs in several genetic conditions including Angelman syndrome, Down syndrome, Rett syndrome, Cohen syndrome and Fragile X syndrome (Landrigan, 2010). These Mendelian disorders present high-risk deficits in social communication. The single gene disorders provide researchers with an important opportunity to study the molecular mechanism involved in aberrant neurodevelopment.

Similar to other neuropsychiatric childhood disorders, ASD has a male bias which is very strong. Male-female ratios are reported to be 1.33:1 to 157:1. Though the severity of autism is not associated with gender, there is clear evidence of differences in gender in presentation specifically in the presence of comorbid features (Jeste & Geschwind, 2014). Males have been observed to have more externalizing symptoms such as hyperactivity stereotypes and aggression while women have more internalizing symptoms including depression and anxiety. In addition, women with ASD tend to have a greater cognitive impairment thought the ration of male-female is close to 1:1 in intellectually disabled people. These findings raise the question of whether the ASD phenotypes are driven by diagnostic biases or biological mechanism which results from a patient’s profile of the disease. ASD diagnosis is a categorical trait and not a quantitative variety (Lord et al.., 2013)

This factor might interrelate significantly with differences in female and male behavior and cognitive styles, as opposed to cognitive ability. A good example is that girls with ASD are normally less overt and disruptive; it is possible for one to contemplate that only girls with more-severe impairment are diagnosed. The knowledge of the differences in management is crucial for clinical presentation, both in therapeutically targeting the most devastating screening and symptoms for specific comorbidities. Some of the researchers have argued that whether gender biases exist or not in diagnosis, there are certain sex-specific biological mechanisms that play a part in the causation of ASD (Jeste & Geschwind, 2014). Based on evidence already existing, the most significant and compelling theory is the female-protective Effect (FPE). The theory suggests that there are specific factors which protect the women from developing ASD. As a consequence of this, females have a greater verge of reaching clinical impairment. This hypothesis has been supported by the fact that there is a greater genetic related load in females than males with ASD.

Autistics like other normal human beings want to live a comfortable life. It is however very hard to sufficiently present the account of autism since it manifests in different ways. According to the latest DSM-V to make a diagnosis of autism, an individual needs to deficits in social interaction and social communication that are very persistent across multiple contexts (Worley & Matson, 2012). However, scholars recognize that there are other features significant to autism and not mentioned in DSM-V. A major feature is language abilities and development which was included in DSM-IV. Another significant feature is motor abnormalities.  A recent analysis by Meng-Chuan, Michael and Simon leaves out under sensitivities and sensory as core features.  However, Temple Grandin argues that it is a key feature in the understanding of autism (Grandin & Panek, 2013).

Autism spectrum disorder is a group of very complex neurodevelopment disorders. It is characterized by patterns of difficulties in social interaction and communication as well as behavior. Landrigan in his study about the environmental contribution to the causes of autism claims that 50 percent of the autistic children have an intellectual disability while others have abnormally increased brain size. Leo Kanner (1943) was the first to describe a group of individual specifically children with the common behavior characteristics in which included social detachment, stereotypical behavior and communication deficits. These symptoms later came to be known as infantile autism. Familiar factors and genetics are involved in the causation of autism. Autism has commonly been observed in twin and sib pairs. Occurrence in monozygotic twins is reported to be as high as 70 percent.

Similar to other neuropsychiatric childhood disorders, ASD has a male bias which is very strong. Male-female ratios are reported to be 1.33:1 to 157:1. Though the severity of autism is not associated with gender, there is clear evidence of differences in gender in presentation specifically in the presence of comorbid features (Jeste & Geschwind, 2014).

References

Chaste, P., & Leboyer, M. (2012). Autism risk factors: genes, environment, and gene-environment interactions. Dialogues Clin Neurosci, 14(3), 281-92.

Grandin, T., & Panek, R. (2013). The autistic brain: Thinking across the spectrum. Houghton Mifflin Harcourt.

Jeste, S. S., & Geschwind, D. H. (2014). Disentangling the heterogeneity of autism spectrum disorder through genetic findings. Nature Reviews Neurology, 10(2), 74-81.

Lord, C., Cook, E. H., Leventhal, B. L., & Amaral, D. G. (2013). Autism spectrum disorders. Autism: The Science of Mental Health, 28, 217.

Landrigan, P. J. (2010). What causes autism? Exploring the environmental contribution. Current opinion in pediatrics, 22(2), 219-225.

National Institute of Mental Health. (2016, March). Autism Spectrum Disorder. Retrieved April 27, 2016, from http://www.nimh.nih.gov/health/topics/autism-spectrum-disorders-asd/index.shtml

National Institute of Neurological Disorders and Stroke. (2016, February 1). Autism Spectrum Disorder Fact Sheet. Retrieved April 27, 2016, from http://www.ninds.nih.gov/disorders/autism/detail_autism.htm

Szatmari, P. (2003). The causes of autism spectrum disorders. Bmj, 326(7382), 173-174.

Timothy, W. Y., Chahrour, M. H., Coulter, M. E., Jiralerspong, S., Okamura-Ikeda, K., Ataman, B., & D’Gama, A. M. (2013). Using whole-exome sequencing to identify inherited causes of autism. Neuron, 77(2), 259-273.

Worley, J. A., & Matson, J. L. (2012). Comparing symptoms of autism spectrum disorders using the current DSM-IV-TR diagnostic criteria and the proposed DSM-V diagnostic criteria. Research in Autism Spectrum Disorders, 6(2), 965-970.

 
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