Is Autism genetic? Indeed a common question among couples with a history of Autism in their family and planning to have a baby. Recent studies have shown that though Autism is primarily a neurological disorder impairing language, communication and social skills, it may have an indirect genetic pre-disposition.
The Center for Disease Control in the United States has estimated that 1 out of every 68 children will be diagnosed to be on the Autism Disorder Spectrum.
While this trend is disturbing, before you get too concerned, it is important to get a bit of background the role of Genes in our lives and the current limitations in genetic studies.
What this page contains
Genes – The Role they Play in Our Lives
The continual investigation being done in the field of autism has led researchers to seek answers to whether autism is genetic. Over the last decade or so, the U.S Department of Health and Human Services has been generously propelling funds to research in the field of Genetics and Genomes – genetics being the study of individual genes while genome is the study of the entire gamut of genes in a human system.
In the Figure, X & Y represents Male or Female. The remaining 22 genes are common to both genders.
Did you know: While a human has 23 pairs of genes, a firefly has only 4. Think of the massive array of genetic combinations across all life forms known to man!
According to researchers, Genes are the basic unit of human composition and are acquired through heredity. A genome is like an instruction manual that determines what species an organism will belong to. Most people, however, are more familiar with the scientific term DNA which is a combination of these genes that provides unique characteristics to every individual within that species – it is our unique racial security number. For example, you and I (being humans) are made of the same Genome but our DNA composition would be distinctively unique.
Causes of Autism – The Role of Heredity?
What we know for a fact is that DNA evolves over generations. With the latest available technologies, scientists are keen to investigate if genes have any role in autism. Studies have been conducted to compare the DNA of autistic children to their parents. As per the analysis of those results, as many as 10% of the autistic children had significant variation in DNA composition when compared to their parents. Children that have siblings with autism also showed some DNA variation (missing or anomaly in genetic structure) when compared to children without any siblings (or having siblings without autism).
Micro-biologists now believe that if a family has more than one child with autism, then either of the parents possessed pre-existing DNA variation (that they might have inherited) and which they subsequently passed on to their offsprings.
Studies have shown irregularities in several areas of the brain as well as abnormal levels of neurotransmitters such as serotonin in the brain.
Compiling this data together suggests there may be a link to the disruption in normal brain development during the early fetal stages and brain cell communication. These types of studies are still in very early stages and require further analysis in order to arrive at definitive conclusions.
Is Autism Genetic?
Genetic inheritance, in scientific terms, is our hereditary gift from our parents which laid the foundations for our genetic map – of whom we were born as and who we will grow up to be.
In acknowledging heredity as part of our very makeup, neurologists suggest that some children have a genetic predisposition to autism; hence implying that autism (in certain cases) may be hereditary.
Studies of identical twins and their families strongly suggest if one twin is affected there is up to a 90% chance that both will be affected with autism. Data from numerous ongoing researches tend to indicate that if one child is born with Autism Spectrum Disorder there is a probability of 1 in 20 that a second child will also be impacted by autism.
Research continues daily and clues are being revealed around how heredity plays a part in autism. Some studies have shown that if a parent has a child with autism spectrum disorder it is very likely either of the parents or a close relative will show very mild impairments in their social skills and were perhaps never diagnosed.
Recent studies by The Cross Disorder Group of the Psychiatric Genomic Consortium have indicated there are indeed genetic and hereditary traits between Autism Spectrum Disorder and bipolar disease, schizophrenia, clinical depression and ADHD (Attention Deficit Hyperactivity Disorder). Evidence suggests these conditions occur more frequently in families with someone diagnosed on the Autism Spectrum than in families without a child with ASD.
Some Known Genetic Traits among ASD cases
Listed below are scientific facts that can determine the risks associated to having an autistic child:
- There is no singular ethnic or socioeconomic discrimination in autism
- Parental age is a risk factor, especially the male partner – fathers tend to pass on 4 times as many genetic defects as mothers.
- Maternal infections such as rubella (German measles) may increase risks around genome deficiencies
- Oxygen Deprivation at the time of birth can kill a few brain neurons
- Premature babies – this aspect is still inconclusive
- Mother’s exposure to chemicals such as valproic acid and thalidomide
A lot of help is available today to help you cope with Autism. There are people, organizations, teachers, schools and therapists well trained in handling Autism Spectrum Disorders. Early diagnosis and intervention are the keys.
Should it Impact my decision to have a Child?.
With cases of Autism Spectrum Disorders rising, parents have a few concerns: What causes autism? Or is autism hereditary? Is there any possibility that I may possess the genome deficiencies and may transmit autism unknowingly to my child? is pregnancy one of the causes of autism? And do early infant vaccines cause autism?
Anne Sue from Autism Rehabilitation says, “Working with children on the Autism Spectrum and their families encourage me to let parents know that having a child is the greatest joy one can experience. There is so much we know now to help bring a healthy and happy child into this beautiful world.”
So the question, “Is Autism Genetic” may not be conclusively answered for the coming few years. While the genetic predisposition has been widely accepted among researchers, a definitive pattern to predict Autism Spectrum Disorder may still not emerge in a near future. And while that gray area remains unresolved, there may not be too many opportunities for any preventive measures. But that should never hinder your decision to have a child – you would lose way more by depriving yourself of this joy!
Latest Research Updates
The culminating factors that give rise to Autism Spectrum Disorders have long been debated upon. As more and more children each year are diagnosed with Autism, researchers are trying their best to find the key causes that lead to this specific disorder.
In an article published in JAMA Psychiatry, on March 4th, scientists from King’s College London (Institute of Psychiatry, Psychology, and Neuroscience), revealed that Autism has much stronger genetic traits than previously determined.
It has long been maintained that Autism, even though, can be genetic in nature, can be influenced by other factors as well. However, this study suggests that genetics has a much more significant presence in autism.
The study was conducted on data derived from the ‘population-based’ Twins Early Development Study’ to determine exactly how much gene and heredity affect autism, because most studies that have been conducted on the topic took in to account ‘clinically ascertained samples’ and in process might have overlooked lesser manifestations of the disorder, thus the estimates derived might not represent the exact picture.
The study took into account all twin pairs born from 1st of January, 1994 to 31st December 1996 in England as well as Wales. The pairs went through a number of tests like the Development and Well-being Assessment (DAWBA) consisting of 359 pairs, with average age 10.3 years; the Childhood Autism Spectrum Test (CAST), consisting of 6423 pairs with an average age of 7.9 years; Autism Diagnostic Observation Schedule (ADOS) on 203 pairs with an average age group of 13.2 years and the Autism Diagnostic Interview-Revised (ADI-R) on 205 pairs where the average age group of 13.2 years.
It was found that the ASD measures and correlations were noticeably higher in the monozygotic twins than the dizygotic twins. In case of monozygotic twins, the range was 0.77 to 0.99 whereas in between the dizygotic twins it was ranging from 0.22 to 0.65, thus attributing almost 56% to 95% to hereditary factors.
The significant finding of the study was that autism was mostly genetic as found among monozygotic twins, even after the rising numbers of affected people and environmental factors has a comparatively much lesser role to play.
According to the co-author of the research paper published, Professor Patrick Bolton, “The comparison of identical and non-identical twins is a well-established way of clarifying the extent of genetic and environmental influences in autism”
With varied and numerous angles that are being studied to get to the root of ASD, this study stands significant, given the larger opinion that Autism is related to factors other than heredity. Even though the numbers are rising, a finding like this can force scientists to let go of environmental issues and study the genetic trails in detail.
For more information, refer to the post on strong genetic predisposition in Autism.