Researchers who have been studying the AGRE data have proposed an explanation of why there are multiple autistics in some families, while other families have only one autistic member:
http://www.pnas.org/cgi/content/full/104/31/12831
They suggest that autism often results from spontaneous mutations in the parental germ line, which are more likely to occur in older parents. Although both male and female offspring are equally likely to have the mutation, females are less likely to be diagnosed with autism. The researchers propose that additional genetic factors moderate incidence in the female gender.
Autism genes resulting from spontaneous mutations are transmitted in a dominant fashion to successive generations of that family, resulting in a 50 percent chance that a son of an autistic father (or of a mother who has the genes, whether or not she is autistic herself) will be autistic, if the other parent has no autism genes.
Because the initial spontaneous mutations vary significantly from one family to another, the researchers are of the opinion that "genetic association studies will fail to find causative mutations."
I hope they're right...
So that means that if both parents is autistic there's at least a 75% chance of autism? If one parent has only autism genes that means he can only get autistic children, but that seems less likely.
Yes, that's correct. If both parents are autistic, then according to this hypothesis the chance of a son being autistic would be either 75% or 100%, depending on whether there was a parent who had two sets of autism genes and thus could have only autistic sons. The chance of a daughter being autistic would be less because of the moderating effect of other genes.
I think it's likely that I have two sets of autism genes, based on my family history (autistic males on both sides). I have a son and a daughter. My son definitely falls somewhere on the spectrum, whereas my daughter is very chatty and sociable and has great face recognition ability. So I'm inclined to think there may be some merit to this hypothesis.
the likey hood is probly more like 50% if both perants carry 25% if one does.
Ok, this is slowly sliding into me now...
... and I realise, that if I have autism, and the autism gene is dominant, at least one of my parents must have it too if excluding the possibility that I could be gene-mutated or having becomed autistic without the genes somehow.
Someone recently said to me that children who are adopted in young ages often develop autistic-like traits because of the traumatic experience of change of family, but I'm not adopted.
I'm not sure whether my mom or my dad or both is autistic. Dad says he looks at people's noses instead of their eyes. When I was bullied at primary dad said to me that he could relate to alot of what I told about my troubles. When we were travelling by car the other day and dad drove, mom was talking about her job as usual and dad followed the conversation politely. When I come to think about it; mom does seldom talk about anything but her job. The other thing might be that she knows everything about actors in movies.
Our family is generally considered as quite, we never yell at eachother. My little sister who I generally think of as über NT is also described as quite.
Researchers who have been studying the AGRE data have proposed an explanation of why there are multiple autistics in some families, while other families have only one autistic member:
http://www.pnas.org/cgi/content/full/104/31/12831
They suggest that autism often results from spontaneous mutations in the parental germ line, which are more likely to occur in older parents. Although both male and female offspring are equally likely to have the mutation, females are less likely to be diagnosed with autism. The researchers propose that additional genetic factors moderate incidence in the female gender.
Autism genes resulting from spontaneous mutations are transmitted in a dominant fashion to successive generations of that family, resulting in a 50 percent chance that a son of an autistic father (or of a mother who has the genes, whether or not she is autistic herself) will be autistic, if the other parent has no autism genes.
Because the initial spontaneous mutations vary significantly from one family to another, the researchers are of the opinion that "genetic association studies will fail to find causative mutations."
I hope they're right...
I notice that on the forums, there are many females with AS either diagnosed or not.
I have a strong suspicion that for some reason the females are not picked up on.
Our family is generally considered as quite, we never yell at eachother. My little sister who I generally think of as über NT is also described as quite.
Quite the opposite, in my family! Strange for AS, or possible?
After sleeping on this another correlate occurred to me -- people who have children later in life are more likely to be affluent. It has already been demonstrated that diagnosis is far more common among affluent families. This makes me wonder exactly what is being measured, incidence or affluence. Many questions.
Because the families are self-selected, I suspect the claim that "the majority of autisms are a result of de novo mutations" is based on a very inaccurate sampling. Families that have several generations of autistics aren't going to want to participate in genetic research that treats dear old Dad like a disease.
But it's possible that the researchers may be correct about how autism is inherited, even if they've got the incidence ratio all wrong.
Interesting sidenote - if this theory proves true, and autistic genes are passed on in a dominant fashion, that means that eventually autistic genes will achieve the same sort of prevalence as right-handedness - i.e. around 75% of the population...
Genetics are strange & interesting.
There is quite a history of 'bonkersness' in my family , paternal & maternal, there certainly are / were some odd / eccentric members as well as diagnosed mentally ill, but equally distributed between the genders.
Therefore it comes as no surprise to find that AS has become common in our family.
What I do find interesting is that there is absolutely no history of colour blindness, some of my deceased relatives were 'career forces members'.
I am obviously a carrier as both of my sons are profoundly colour blind, but it would seem on the face of it that this was a spontaneous mutation, but at the same time according to genetic rules only 50% of my male children should have it.
Perhaps in my case, it is not only 'new', but also dominant ( I see slightly different colours with each eye ).
Well, I am 37. I'm almost as old as my dad when he and Mom made me. More ammunition not to have kids.
I dislike it when parents at the norwegian board tell they are afraid of getting another autistic child, but I think it would be unwise to comment it there.
I dislike it when parents at the norwegian board tell they are afraid of getting another autistic child, but I think it would be unwise to comment it there.
I am glad that all of our children are on the spectrum. They "get" each other, and there is a notable lack of any type of nastiness between them. They argue and fight, but it is always a straight forward affair and once it's over, it's over.
I am glad that all of our children are on the spectrum. They "get" each other, and there is a notable lack of any type of nastiness between them. They argue and fight, but it is always a straight forward affair and once it's over, it's over.
Same here & with me, that make three of us in our family.
So we're officially mutants now? Yay us!
Alison