Autism is a type of developmental disability whereby the individual suffers from a cognitive deficit, impaired social interaction and difficulties integrating with the people around them. The neurodevelopment disorder affects about one in every 88 children in the USA and the Centre for Disease Control and Prevention estimates that 36,500 of every 4 million children born will be affected by autism. Most autism sufferers are male. Interestingly, studies have found a consistent increase in the number of cases of autism but no satisfactory explanation has been given for this increase.

Autism Spectrum Disorder

Autism manifests itself in many ways and to varying degrees. Each autistic individual is unique and any treatment needs to thereby be tailored to the needs of that specific individual. Not all autistic children will suffer from the condition with the same severity and there will be marked differences from one individual to the next. These variations and continuum within the very notion of autism have led psychologists and other experts in the field to refer to the condition as autism spectrum disorder or ASD. Originally, different types of autism were treated and identified separately, as if each were a disease of its own. Following the last DSM-5 diagnostic manual, published by the American Psychiatric Association and published in 2012, all autistic disorders have been encapsulated under the term Autism Spectrum Disorder.

The Genetics of Autism

  • Whilst scientists are far from understanding Autism completely, they do know that both environmental and genetic factors could play a role. With regards to the genetic component of autism, no single gene has been identified but rather a number of genes or genetic mutations seem to be the possible culprits. Scientists believe that any of the several genes which play a role in the development of the brain could be potentially involved in the development of autism. It is a highly complex and dynamic area which involves genes, protein synthesis and neurotransmitters.  Here are just a few: EN2 (homeobox gene that is critical to the development of the midbrain and cerebellum),
  • Reelin (a protein),
  • GABRB3 (an inhibitory neurotransmitter in the adult brain),
  • serotonin (a neurotransmitter that is known to affect mood and social behaviour)
  • 5-HTT (a serotonin transporter protein
  • FOXP2 (a protein required for proper development of speech and language).

But genetics alone are unlikely to be the sole cause of autism and certain environmental factors seem to bear a quasi-equal importance in the development of the condition. Certain people will have a genetic predisposition to autism. This means that they will be carriers of the disease-causing genes but these genes alone will simply predispose them to autism. The disorder will only manifest itself if certain socio-environmental conditions are met which would normally take place in the prenatal/antenatal stage or in the 2-3 years following birth. The following are some factors which have been identified: getting pregnant at an advanced age and complications during pregnancy.

Unfortunately, although many genes have been identified, the current DNA tests or genetic predisposition tests available on the market by companies do not included testing for this condition.

Autism affects both the person’s communicative skills, with an often exhibited reluctance or refusal to communicate with people, as well as the person’s developmental skills. These individuals may have intellectual disabilities, poor motor skills and poor coordination. They also often suffer from gastrointestinal disturbances such as Colitis, Gastritis, IBS, constipation as well as food allergies and sensitivities. Some autistic individuals may have selective interactions with others, whereby they will only hold conversations with a specific person or people but eschew communication with anybody else. Often they will altogether refuse to engage in the slightest way with anyone besides that select person/people.

Depending on the severity of the condition, the person may be able to lead a perfectly normal life or be entirely hampered by the condition. The autistic person’s ability to lead a normal live is heavily influenced by the way they perceive the world around them through their 5 senses (touch, sight, smell, sound and taste). Often, they suffer from sensory integration difficulties / sensory processing disorders. When we perceive a sound, sight, smell, taste or palpable touch, our brain processes the information which then translates into certain motor and behavioral responses. The brain of the autistic child will however, process these sensory experiences in a different way; the experience of these sensory stimuli do not translate into normal/appropriate responses. A person with a sensory processing disorder may display apathy or indifference to extreme pain or suffering or may display an extreme show of emotion when they notice a pitch increase in a person’s voice. An autistic child might also have Synesthesia, where associations are made between mismatching senses; a person with Synesthesia might be able to see sound or hear smells. Some autistic children exhibit exceptionally fine visual skills and are talented in art, math or music. Again the degree to which these and other symptoms of autism affect the sufferer, will determine their ability to integrate with society and lead normal or atypical lives. More about the signs and symptoms of Autism may be found by clicking here.

The Hereditary aspect

Autism is hereditary or, perhaps more correctly, there is a hereditary genetic component to autism. This finding is based on twin zygosity studies which have consistently shown an increased incidence of autism in monozygotic twins when compared to dizygotic twins. Monozygotic twins (identical twins) are genetic clones of each other with the exact, same DNA profile. This means that any genes found on the DNA of one twin will also be found on the DNA of the other twin. The chances of identical twins both being autistic could be anywhere between 36-91% whilst dizygotic twins have a 2-4 % chance. Further information on the hereditary factors and twin DNA testing studies can be found here.

If you have had a first child who suffers from autism, the chances of your second child being autistic are pretty low. Scientists estimate a recurrence risk of autism is between 2-6%.

When talking about the hereditary or genetic aspect of autism we should also take into consideration “syndromic” and “non-syndromic” autism. Autism is, in some cases, secondary to other conditions such as fragile X syndrome or Rett syndrome. When it is associated with a neurological disorder such as the aforementioned examples, it is referred to as syndromic. In other words, autism would not be the primary diagnosis if the individual suffers from fragile X syndrome or Rett syndrome. If autism is the primary diagnosis, we refer to it as non-syndromic autism. Non syndromic autism accounts for the vast majority of cases and these cases have no identifiable underlying causes – the sufferer does not suffer from either Fragile X syndrome, Rett syndrome, Smith-Lemli-Opitz syndrome, tuberous sclerosis or any of a range of other possible neurological disorders.

Bibliography

En.wikipedia.org. (2017). Autism. [online] Available at: https://en.wikipedia.org/wiki/Autism [Accessed 08 Feb. 2017].

Dnalc.org. (2017). Autism Candidate Genes : DNA Learning Center. [online] Available at: https://www.dnalc.org/view/908-Autism-Candidate-Genes.html [Accessed 10 Feb. 2017].

CDC – Facts about Autism Spectrum Disorders – NCBDDD. (2017). Facts About ASDs. [online] Available at: https://www.cdc.gov/ncbddd/autism/index.html [Accessed 14 Feb. 2017]

Psychiatry.org. (2017). Get Help With Autism. [online] Available at: https://www.psychiatry.org/patients-families/autism[Accessed 14 Feb. 2017].

What Is Autism?. [online] Medicalnewstoday.com. Available at: http://www.medicalnewstoday.com/info/autism [Accessed 14 Feb. 2017].

 

This is a sponsored post by General Genetics Corporation.

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