Given today's growing developments in genetics, it is hardly surprising that they have found two genes on chromosome 6 strongly linked with dyslexia, and a gene that strongly predisposes people for schizophrenia (via the November 5, 2005 issue of Science News).
This is part of a bigger picture, however. Week after week, month after month, we discover new genetic markers for serious physical and mental disorders (a distinctions that is growing more and more dubious). Tenantive or definitive genetic links have been found to Crohn's disease, Alzheimer's disease, cystic fibrosis (and a related condition involving succeptibility to sinus infections), lumbar-disk disease, breast cancers, kidney cancers, pancreatic cancers, esophageal cancers, early aging syndrome, Lou Gehrig's disease (ALS), type 2 diabetes, bipolar disorder, atrial fibrillation (a type of heart disease), muscular dystrophy, sickle cell anemia, familial dysautonomia (a nervous system disorder), and achromatopsia (color blindness due to a lack of cones in the eyes). Some diseases which were thought to have been identical, turn out to have multiple strains, some genetic and some not.
It isn't terribly new. The genetic basis for hemophilia has been known since the dawn of modern genetics, because it was found in European royal families. But, the big picture is changing. More and more disorders are linked to genes, increasingly genes that simply put you at a high risk of developing a problem, rather than one the definitively determines whether or not you have the diease. At the same time, genetic tests become increasingly inexpensive to conduct -- sometimes allowing technicians to simply drop a bit of blood or salavia into a handheld, mass produced testing device. It will soon be practical to routinely check children for hundreds of known markers for genetic disorders. The economics make sense. Even if the entire regime costs $1,000 or more, they need to be done only once in a lifetime. This would allow doctors to quickly rule out a diagnosis of hereditary diseases later in life, while focusing on dealing with the real issues behind an ailment.
Unfortunately, as we develop better and better understandings of our genome, we learn that most of us have some flaw or another, and are carriers for many more. Not all are necessarily life threatening. You may be predisposed to adult acne or may have a genetic predisposition to snore. And, some may even be good. You may have the "long life" genes that help allow your body to process cholesterols exceptionally well, or a rare natural resistance to HIV.
But, in a society where insurance is based on not being able to know in advance whether someone will get sick or not, the most serious threats to a person's health may be viewed by an insurance company as known pre-existing conditions that it shouldn't have to cover. From the company's perspective, why should it pay claims on a sure or likely loss that exceed the premiums it charges?
Thus, advances in genetics may end up posing as much of a threat to the private health insurance systems used in a handful of countries including the United States today, as any of its other problems.