Posts Tagged ‘ Genetics ’

Why Is Autism So Common Now?

Monday, April 1st, 2013

Autism RibbonIn 1980, the rate of autism was typically quoted as 4 in 10,000. The most recent rate reported is 1 in 50. While it is difficult to get a precise estimate, it’s abundantly clear that rates of autism have increased dramatically since 1980 – and in fact over the last decade. So what has changed?

There are a number of factors that have brought the startling levels of autism to our attention. These include:

Better Awareness: In 1980, autism was first introduced as a separate diagnostic category in the third addition of the Diagnostic and Statistical Manual of Mental Disorders (DSM). Prior to that time, clinicians using the DSM applied other categories such as childhood schizophrenia. Since 1980, there has been extraordinary growth in awareness – both for professionals and parents alike. This is particularly so over the past decade. Advocacy groups have done an admirable job of helping us understand what autism is (and isn’t). Pediatricians now screen for early warning signs – as do parents. These actions have all led to a much greater awareness of the symptoms of autism which undoubtedly translates in more proper diagnoses being made. In addition, the increased awareness has permitted older kids to be diagnosed more properly when the signs earlier in life were not recognized as autism.

Expansion Of The Symptoms: In parallel with efforts to increase awareness, diagnostic changes that recognized autism as a spectrum – now referred to as Autism Spectrum Disorder (ASD) – helped capture the wide range of symptoms that go beyond “classic” autism. Including a much broader representation of social, communicative, and repetitive/stereotyped behaviors certainly helped recognize the disorder in many youth who would not have been diagnosed in past years. Of course, there is debate about how the changes in the upcoming DSM-5 may result in a reduction in the rate of diagnosed ASD in the future. But up until now, recognizing the variation in symptoms that can characterize ASD has certainly been a factor in understanding how common autism really is.

Changes In Etiological Factors: Less understood is the role of new causative factors that increase risk for ASD. Much attention is being given to a large number of potential environmental contributors. There is the suggestion that specific genetic mutations that may be linked to autism – and associated with paternal age – are more common in the population because of average increases in paternal age over the last few decades. Much of this work, though, is work in progress, as it is believed that ASD typically results from the combination of a number of environmental and genetic risk factors. But many researchers operate under the assumption that there are both environmental and genetic risk factors that may be increasing in the population, though they remain elusive.

So, since 1980, what we have learned? We know now that autism is very common, is best thought of as a spectrum that includes substantial variation in how symptoms are expressed, and may be influenced by increasing levels of risk factors that are not well understood at this time. For all these reasons, it is critical that we keep researching the causes of autism, and continue to promote awareness of the early signs and symptoms in order to support early diagnosis and intervention.

Image: Autism Awareness Ribbon via Shutterstock

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Childhood Psychiatric Disorders: Will Genetic Engineering Ever Be A Solution?

Wednesday, February 27th, 2013

Following a stimulating Intelligence Squared debate, we’ve been discussing genetic engineering (think of it as directly changing DNA) here at Parents.com – both in terms of using it to create a “Super Baby” and to prevent disease. As a follow-up, let’s consider the likelihood of genetic engineering being a factor in the future for a number of childhood psychiatric disorders – or more to the point, the challenges that lay ahead. 

Autism Spectrum Disorder (ASD)

There would be hope that genetic engineering would be feasible in the future, as ASD is believed to be highly genetic in origin. However, the genetic basis for ASD is not clear. In fact, there may be a range of genetic etiologies. For example, some cases may be due to a rare genetic mutation – but there could be a number of mutations that can lead to ASD (not just one identified disease gene) making the idea of genetic engineering more challenging. The majority of ASD cases may reflect a complex mix of genetic and environmental influences – and the latest statistical modeling suggests that the genetic contribution to ASD may not be as strong as previously thought (and that the role of the environment may be more pronounced). For those situations, the idea of using genetic engineering is even more murky, because there may be many genes involved and they probably interact with a variety of environmental factors. All of this is not to say that genetics won’t lead to possible biological therapeutics – rather it’s to point out that the lure of genetic engineering as a solution may not be the avenue that will be pursued.

ADHD

The best evidence to date suggests that ADHD is due to a mix of genetic factors along with the influence of a number of environmental factors. As discussed above, this makes the pure application of genetic engineering difficult to imagine. There may a large number of genes involved, each of which may only have a small effect on the likelihood of developing ADHD – which, simply put, would make it very difficult to know what genes to target. Again, it’s tough to predict where genetic research will go, but while it may certainly lead to improved treatments over time for ADHD, it’s tough to see the role of genetic engineering.

Depression

You’re starting to see a pattern here. Like ADHD, depression is also thought to be influenced by many genes as well as the environment. As discussed above, this constellation of risk factors does not suggest that genetic engineering will be a factor any time soon.

Conduct Disorder (CD)

This is the same deal as the case for ADHD and depression – and it may be that the environment plays an even stronger role in the etiology of CD.

Conclusion

The idea of genetic engineering is provocative. But the reality may be far in the future for most childhood psychiatric disorders – and in many cases it may not be the way in which genetic research gets translated into prevention and intervention.

Molecular Biology Test via Shutterstock.com

 

 

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Genetically Engineered Babies: Good Or Bad Idea?

Wednesday, February 20th, 2013

Would you want the option of harnessing the power of genetics to alter the DNA of your unborn child? Would you want this to prevent disease? Select physical characteristics? Or “design” your baby by changing the genetic code? 

Such was the topic of an Intelligence Squared debate held in New York City on February 13. Two experts argued that genetic engineering should be banned; two experts argued that it should be supported. The audience – of which I was a part – had a chance to vote both before, and after, the arguments were made. Prior to the debate, I was in favor of supporting genetic engineering – with many caveats. After listening to both sides present their point of view, I pondered three points to help me come to a final decision:

Is genetic engineering feasible?

The science of genetics is fast paced. Although we don’t have much in the way of actual examples, it is worth assuming that it would be feasible at some point in the future. That said, my position is that it will only be worth considering for diseases or traits that are shaped by a single gene. There are certainly many diseases for which this is the case, such as cystic fibrosis and Huntington Disease. I certainly think there may come a time when it would be possible to try to intervene biologically to correct the mutations that underlie these conditions. However, bear in mind that most diseases and traits are believed to be due to the effects of many genes (polygenic) as well as environmental influences (multifactorial). Even height, which we think of as being “genetic”, is due to the combined effects of many genes as well as environment, and hence is multifactorial. Eye color is not as straightforward in terms of genetics as you might think. So … I think we can have the conversation about those more rare diseases and traits that are due to the “necessary and sufficient” effects of a single gene which can be identified along with the gene product. Having the debate about polygenic and multifactorial traits (more on this below) seems to be morphing into science fiction rather than science (unless science proves that wrong).

Why should we pursue it?

The primary reason would be to eradicate disease, especially disorders that are known to cause premature death. Certainly think about the life of a kid with cystic fibrosis – who wouldn’t want to spare a child that? Huntington Disease is an interesting example because it reveals that genes don’t just express themselves at birth – they can have a deleterious effect in adulthood. If we could alter that gene and prevent Huntington Disease, shouldn’t we do that? Some cases of breast cancer involve the primary (though not fully deterministic) effects of a single gene – again, if we could alter that mutation, wouldn’t we do that?

Why shouldn’t we pursue it?

Many feel that there are ethical considerations. For example, some do not like the idea of changing DNA – in essence, the thought is that it should be left alone. However, in terms of disease treatment, it’s worth noting that we do have examples of changing what a mutation does, and in the process keeping people healthy. A great example is a type of lymphoma caused by the “Philadelphia Chromosome” (so named because the mutation was discovered by scientists at the University of Pennsylvania). While the discovery was made in 1960, it took about 40 years to discover a genetically tailored drug that keeps the disease in check and allows people with this mutation to lead healthy lives. Although this isn’t genetic engineering in the strict sense, the principle is the same – alter the effects of DNA to change the likelihood of disease.

Less clarity surrounds the use of  genetic engineering to try to give parents the opportunity to control a variety of traits in their child to be – their appearance, personality, intelligence. As discussed by Melanie Abrahams, the pregnancy editor at Parents.com, the issue is would you want to create a Super Baby if you were given the choice? Again, my two cents to throw into this part of the debate is that it’s hard for me to imagine genetic engineering for polygenic, multifactorial traits – which includes appearance, personality, and intelligence. But then again, we don’t really know, do we?

Where do I land on this issue?

Bottom line, I support the idea of genetic engineering for well-defined diseases that are known to cause suffering and death. I don’t see any difference between designing a drug that is tailored to counter the biological effects of a mutation, and in principle directly altering the mutation. I don’t like the idea of applying genetic engineering principles to anything other than disease. Even “black or white” questions have their gray area.

DNA Structure via Shutterstock.com

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A (Very Brief) Primer On Genetics And Behavioral/Emotional/Developmental Disorders

Wednesday, November 28th, 2012

This will be brief.

There continues to be loads of information on the role of genetics on behavioral/emotional/developmental disorders. This pace will continue. But the big picture for parents can be elusive. So here is a primer.

Some disorders  are “genetic” in the classic sense—meaning they primarily have a genetic foundation. They tend to be very rare and distinctive. Examples are Fragile-X syndrome, and Down syndrome.

That said, most disorders these days are assumed to be “complex”—meaning that they arise from a combination of risk factors, both genetic and non-genetic in origin. In many cases, there may not be “one” definitive etiology but rather a range of causes that can vary from kid to kid. For example, it is believed that some cases of autism are due to rare genetic mutations (some of which may be associated with paternal age). But this type of causation may only account for a small fraction of the cases in the population. There may be a number of genes (some suggest it could be in the hundreds) that convey some level of risk for autism. And for these cases, the environment can also be a potent influence, as evidenced by recent twin studies. That said, the actual environmental factors remain elusive.

This idea of “complex” causation probably applies to the vast majority of behavioral/emotional/developmental disorders. ADHD is believed to be highly heritable—but there are no genetic markers that distinguish normative levels of inattention and hyperactivity from problematic ones. And just because ADHD is heritable, that doesn’t mean that the environment doesn’t matter. Biological environments (such as prenatal exposures) may play a role. The psychosocial environment is also very important in terms of shaping how ADHD gets expressed. In the case of “complex” disorders, genetics is often described as influencing “what is,” but not “what can be”—which is another way of saying that psychosocial interventions can be powerful approaches for altering behaviors that are “genetic” in origin.

We’ve learned a lot about genetics over the past few decades. We will continue to learn even more. But the reality right now is that, with the exception of rare “genetic” disorders, there is still more unknown than known about the role that genes play in the evolution of behavioral/emotional/developmental disorders. What we do know, though, is that environment matters. So whether we are talking about autism or ADHD or conduct problems or other issues, a parent’s best line of action is to get reputable psychosocial interventions that have been shown to work. Remember, genetics is, more times than not, more about “what is” rather than “what can be.”

Lab Experiment via Shutterstock.com

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Is There A Mom Gene?

Friday, September 28th, 2012

Just after a wrote a blog post on how there is a whole new level of complexity in studying how genes work, I see that the internet is lit up with news of the discovery of the mom gene. And speculation about what it means for women, reflections by writers on whether or not they have it, and so on. So … do you have the mom gene? 

Well, at this point, the only way you can determine this is if you are … a female mouse. (And even that is still subject to debate).

Yes, check out the abstract of the study here. It’s an important study. It’s a well conducted study. It’s published in a top tier journal. But it is about maternal behavior in mice.

Now, of course there is a long history of using animal models to inform our understanding of human behavior, particularly with respect to neurobiology and genetics. And this study is going to make a scientific contribution to understanding how specific genes may play a role in regulating specific and complex behaviors. But that said, how do we go from the following – “Suppression of ERα in the preoptic area almost completely abolished maternal care, significantly increasing the latency to pup retrieval and significantly reducing the time the moms spent nursing and licking the pups” (from the study’s abstract) – to making inferences about the degree to which human females are predisposed genetically to want to be a mother. As if you could run to your local geneticist and ask for a rapid genotyping so you can find out for sure if you really want to be a mother.

Look, I’m all for interesting research on genetics. I’m for understanding how genetic influences shape in part complex behaviors in humans (I’ve spent a fair number of years studying this). But can we get back to reality? We can’t find single genes for the vast majority of diseases – primarily because they involve complex (and not understood) interactions between biology and the environment. The science of genetics keeps getting more and more complex. When we talk about wanting to be a mother, think about how many social factors are involved from early childhood through adulthood (I know I’m stating the obvious, but it seems like the obvious needs stating). No complex human behavior is reducible to a single gene that functions in a “go/no go” way. Do genes play some type of role in how strongly a female wants to be a mother, or how maternal she is? I’m sure they do – in the same way that they have some influence on shyness, or aggression, or any number of traits, along with a whole bunch of social and cultural factors.

So, I can confidently state that unless you are a female mouse, we are not, at this moment in scientific time, ready to determine if you have, or don’t have, the mom gene.

Mouse mom with pups via Shutterstock.com (I guess this mouse has the mom gene)

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