Disease or variation?

I've ended up in an interesting discussion on another blog (Dust in a Sunbeam by Optimus Primate, check him out), which through a serpentine route became the topic de jour at lunch today. Long argument made short, many of the diseases and conditions we previously thought were due to abnormal development are beginning - in some cases - to appear to be nothing more than the extremes of humanities evolution-derived biology.

Autism is the case that brought this up, and makes for a great example. Autism is a genetic disorder - there are literally dozens of genes that, if present in the right combinations of alleles, cause autism. But, these same genes appear in non-autistic individuals, and in some cases the "autism" alleles may actually lead to better intelligence, or greater artistic/mathmatic ability. Indeed, some of history's greatest scientists, artists & mathematicians may very well have been autistic (Einstein, Beethoven, Mozart, Yeats, Darwin and Turing as examples).

As we uncover more and more of autistic biology its beginning to look less like a disease, and more like a little piece of human evolution that is skewed in one direction. Autism is the genetic opposite of schizophrenia (i.e. "autistic" genes prevent schizophrenia, and vice-versa), and in many ways is also the behavioural opposite. As it turns out, the very genes that cause these two "diseases" are also those genes that appear to have changed while we humans developed our intelligence. The list of genes that cause these disorders reads like a list of neurological genes that changed as we evolved from our ape-like ancestors - FoxP3, Microcephalin, and so forth.

Likewise, as we learn more about these diseases the barrier between "disease" and "normal" grows faint. Aspergers patients (a "mild" form of autism) are often more intelligent than neuronormal individuals, appearing to many as super-shy individuals and nothing more. And their "normal" parents often score below "normal" on many of the tests used to ID autistics. The same is true of schizophrenia; between the "disease" and "normal" is a huge range of people, exhibiting behaviours that while odd are a far cry from being a disease.

The net effect of this is that these "diseases" may not be diseases in the classical sense of the term, and instead simply represent the "tails" of normal human variation. This, in my mind, brings up a couple of serious ethical questions. And as our understanding of the causes of these "diseases" increase, they are questions we will need to seriously consider before developing therapies:

1. Is it right to treat part of normal human variability as a disease?
2. Are the symptoms of these individuals truly something we need to intercede with? (This is an especially thorny question when talking about individuals on the "mild" end of the spectrum).
3. Do we have the "right" to label genetic variation as a disease, and the "right" to mess with it?

Autism puts these questions into stark contrast. We now know that many of the genes mutated in autistics are the very genes that mutated to give rise to human intelligence. We know, based on the "symptoms" of autistics, that these genes have an important role in determining how our brains work. We also know that some of these genes, when put together into the right combination, lead to amazing leaps in intelligence - savantism for example. Likewise, we know that many of these genes are actively evolving today.

These question may seem philosophical in nature - what "right" do we have to tell someone they are diseased, etc. But we are on the cusp of being able to alter our own genetics, and when that day comes this issue will be propelled from a philisophical issue to one which is very pertinent. We don't know why the genes that cause autism (or schizophrenia) have been maintained by evolution. We don't know if these variants are important in maintaining human intelligence. And we have no idea what future role they will play in the humankinds ongoing evolutionary story. Any treatment for autism could very well quell the next step in the evolution of the human brain.

Its a sharp knife - on one side we have the health and well being of people to worry about; but on the other side of the blade could very well lie humanities future.