Can Autism Be Inherited?

Let’s think that there is a couple who want to be a parent and one of them has an autism spectrum disorder. Everyone thinks that their child would have autism in high chance. Actually, we know that if it is a severe case, there is not a chance to marry and have a baby because they cannot survive by themselves. Nevertheless, if it is mild autism or Asperger’s syndrome, they can marry and they can have a child.

After that point, it is the case that should be considered which is whether their child has autism or not. In this article, I will try to explain how things are going on in these circumstances. What are the chances of having a child with autism spectrum disorder? What percentage is that? Or even is there a percentage like that? If there is a heritage like this, this link comes from which parent?

Even though the inheritance pattern is usually not known, autism spectrum disorder has a tendency to run in families. Generally, rather than the condition itself, individuals with gene mutations which are associated with autism inherit an increased risk of developing the condition. 



Genetic Mutation vs Genetic Heritage


Autism spectrum disorder is an accident of birth. There is no exact cause for it. As far as we know, it is a genetic condition, even though we cannot say that for sure, nor that this is the sole determinant.

Besides mutation and heritage, it may also have to do with the environment. Bu the environment part, if is there any effect, is that of the womb as the brain pathways of autism are in place long before birth.

The genetic factor could be either a mutation or inherited from one or two parents. Even in these options, we cannot say for sure that which one causes autism.

It comes from neither parent but from a mistake in code translation early in gestation in case of mutation. Most mutations result in no important change and remain harmless, perhaps a tiny change such as a difference of eye color. Some mutations are neither fatal, for example, the fetus does not gestate fully and miscarries, nor in rare situations results in a birth, or even a baby fails shortly after birth. Furthermore, the remaining mutations result in disorders. Autism spectrum disorder is one of them. Although it is nonfatal, it is a definitely different variation on the human brain.



It could be inherited from one or both parent in case of genetic heritage. In the case of dominant trait, either parent may have it and may contribute it in the half of their DNS that their child gets. In other respect, in the case of a recessive trait, both parents contribute this trait for the child in order to have that trait. There is no exact indication that this trait comes from the Y chromosome, so we can say that either the father or mother can contribute it. Nevertheless, we do not know whether it is dominant or recessive.

We know that it is complicated. At the basic level, it could be either one, it could be both or maybe more than that. We cannot point to all mothers, all father or anyone on the spectrum in the family as the cause of having autism.

Can Autism Be Inherited from Parents?


We know that there is no single gene that causes autism spectrum disorder when it is mutated. Researchers have identified hundreds of gene variations that affect brain development, increasing the risk of having autism. However, these researchers mainly investigated variants in DNA that directly encode the building blocks of proteins.



In today’s world, there is a new study which is called non-coding DNA has found that changes in regions regulating gene activity may also be associated with an autism spectrum disorder. And surprisingly, these variations tend to inherit from fathers who do not have autism. This study makes us think in a different way about the genetics of autism. So, we can say that this is a great contribution to the field.

Research on genetic risk factors focuses on how spontaneous mutations in an individual’s genome occur. Fundamentally, it is necessary to focus on genes inherited from one of the parents, protein-coding regions, and genes that cause autism.

These sporadic mutations, which means rare and scattered in occurrence, have relatively large effects. Studies have shown that these rare mutations contribute to approximately 25% to 30% of cases. In other respect, only %2 of the genome consists of protein-coding areas. The largely non-coding part of our DNA, which was previously called “junk DNA”, has been ignored so far in autism research.

Researchers have been particularly interested in portions of non-coding DNA that regulate gene expression. They looked at all genome sequences from families, including individuals with an autism spectrum disorder, their siblings without autism spectrum disorder and their parents. Evaluation of the effects of individual DNA base changes is more difficult, especially in non-coding regions. Thus, it has identified larger changes, which are called structural variants, in which large DNA sequences are inverted, duplicated, or deleted.



Each individual has lots of structural variants in their genome, as we know. Researchers narrowed their analysis in order to examine a handful of regulatory regions that appear to be degrading genetic diversity. They found regions where the general population had less variation than expected and then they selected them. This suggests that genetic changes may be harmful. These include sites that regulate gene activity during brain development and initiate the transcription of genes.

Then, researchers examined whether the structural variants in these regions were related to autism by transmitting from parents to children with autism and children without autism. It has been assumed that mothers are more likely to pass autism-causing gene variants than fathers. Because of the fact that the rate of autism spectrum disorder in women is lower than in men and it is thought that women can carry the same genetic risk factors without any sign of autism. However, when a mother passes on these genes to her sons, they are not protected and affected in the same way.

There is a female protective effect in this case. According to that theory, women are somehow protected from mutations that might trigger autism spectrum disorder, however, sometimes they pass the mutations down to their sons.



Mothers pass only half of their structural variants at a frequency that can only be by chance. So, it can be claimed that variants which are inherited from mothers may not be associated with autism. On the other hand, surprisingly fathers pass more than 50% of their variants to the next generation. This suggests that children with autism may receive risk variants in regulatory areas from their fathers, not their mothers.

As a result, we can say that there are inconsistent findings of the heritability of autism. Autism could stem from a combination of a powerful coding mutation that is inherited from the mother and a less powerful noncoding mutation which is inherited from the father.

Can Autism Be Inherited from Siblings?


There is a risk that a brother or sister of an individual with idiopathic autism which is of unknown cause might developed autism spectrum disorder is around 4%. Also, there is an additional 4% to 6% risk for a milder condition includes symptoms related to language, social and behavioral.

Brother has a higher risk of developing autism spectrum disorder compared to sister, which is about 7%. Also, there is an additional 7% risk of milder autism symptoms, over sisters whose risk is only about %1 to %2.

The causes of autism spectrum disorder could be divided into two categories. They are idiopathic which is the majority of cases and it is of unknown cause and secondary causes in which a chromosome abnormality. In this case, single-gene disorder or environmental agent can be identified. While approximately 15% of individuals with autism can be diagnosed with secondary autism, the remaining can be diagnosed with idiopathic autism.

When the case comes to the siblings, things mostly depend on secondary autism. When the cause of autism is a chromosome abnormality, the risk that other sibling will also have autism depends on the specific genetic cause.



Who Causes Autism?


It is not a simple question to answer because it is not that simple condition. And also, there is no need to look for someone to blame. That does not make any sense at some point. Because if you have a child with autism, you have a child with autism anyway. It is not anyone’s fault. No one can control what their own genes do or what the genes of their offspring do.

Autism spectrum disorder is not due to mistreatment, trauma or bad parenting. Even if a lot of people tried to insist that was true 60 years ago or so, but in today’s world, this whole idea was proved wrong. On the other hand, if an individual has autism and that person is mistreated, it is certainly a bad situation. It will definitely cause the person emotional pain, just as abuse would cause any person emotional pain.

Nevertheless, autism spectrum disorder is due to misspellings in multiple different genes that all of us have. As far as we know, there is no special gene for autism. No one inherits an autism gene from anyone. No one inherits the gene from the father, the mother, the siblings or any previous ancestor. It just does not work that way. It could be gene mutations.

After all these researches, there is a new perspective about the issue who causes autism. Instead, individuals with autism have multiple misspellings in genes, these misspellings in their genes result in very small errors which are being made in the development of the unborn child’s brain.

Misspelling genes are responsible for directing and controlling fetal brain development. There are million possible genes which could have misspellings. It varies from one individual with autism to another. For example, in some of them, there could be many large misspellings in their genes which leads to a more severe form of autism. On the other hand, in some of them, there could be fewer misspellings and they lead to less severe form or mild form of autism.



As it was mentioned above, instead of who causes autism, there is another view about that which is misspellings. Gene misspellings quite often happen on their own for no reason. So we can say that no one causes having autism. No one does anything wrong.

As further information, it is possible that the parent could have a very small misspelling in one location on a gene, however, then the child could wind up having a very large misspelling at that same location in the gene. Again, it is a random occurrence and no one’s fault. It is a very important point that should be kept in mind.

In addition, some gene misspellings could be inherited at some point. For instance, a parent with mental disorder such as schizophrenia, bipolar disorder, intellectual disability or simply autism spectrum disorder could possibly pass along gene misspellings to his/her offspring. Furthermore, it can increase the risk of multiple conditions. For example, gene misspellings can increase the risk of getting a number of different disorders at the same time. These could be inherited.

As mentioned before, it is a complex and not predictable issue, even if a parent has an autism spectrum disorder or Asperger’s syndrome. Even if the father or mother has autism, the risk of their child having that condition is not 100%. It is expected because there are multiple genes involved.

As a result, it can be said that gene misspellings happen all the time. They are not entirely, 100% consistent or predictable. It can be overwhelming to live with autism itself or with someone who has autism. You may need to blaming someone for this condition. But, it is not helpful at all. The best thing you can do is getting professional help. It may help you to overcome, to understand what exactly makes you upset or at least it may teach you how to live with it.

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