A recent study has shown that five distinct psychiatric disorders – namely autism, attention deficit hyperactivity disorder (ADHD), schizophrenia, major depression and bipolar disorder – share the same genetic mutations, apparently advancing the notion that gene mutation is not exclusive to just one psychiatric illness.
Dr. Vicente G. Rosales, Jr., professor at the University of Santo Tomas Department of Neurology and Psychiatry, indicated thus at the 41st National Convention of the Philippine Psychiatric Association (PPA) held recently at Edsa Shangrila Hotel, as he lectured on the clinical utility of genetic markers in the treatment of bipolar disorders.
“So if I have a gene mutation at such an early age, I can end up being autistic, depressive, schizophrenic or I can end up being all five since there’s no exclusivity,” he said. “All those genetic markers that are mutated in the five psychiatric disorders beg the question why, if they share something physiologically such as mutation or alteration in the gene sequence, we make so much fuss in trying to come up with empirical classifications system? We try to segregate or compartmentalize each disorder in defiance of the fact that they share common genetic problems.”
A genetic marker, from the physiological standpoint, is simply a gene or DNA sequence with a known location in a chromosome. Dr. Rosales explained that a gene or DNA sequence is polymorphic, or there may be different ways by which the manifestation is shown.
“For instance, regarding hair color – I have black hair, somebody has brown hair. We all have the same number of genes except that my genes will eventually manifest as black hair in me. Since I know the location of the gene for black hair, it means it is a genetic marker,” he continued. “On the other hand, you can use the genetic markers in pathological settings. There are many different diseases that can actually be very hereditary or genetic and the reason why they’re pathologic or why they give you illness is because apparently the gene became altered or mutated from one generation to another due to exposure, toxic materials, or radiation.”
In practical application, genetic markers are used for paternity testing and to trace distinct traits that are passed on from parents to offspring by heredity. “But more importantly however, you try to trace the inheritance and history of genetic disease,” Dr. Rosales said. “The number one illness that comes to mind which is genetically transferred is diabetes mellitus. Another is osteoporosis. For psychiatric illness, it is schizophrenia and bipolar disorder. That is why it is so important to get family histories.”
The ability to understand the susceptibility of a person to disease because of his genes becomes a powerful tool in preventing such disease. “For instance,” he explained, “if you have a strong family history of osteoporosis, you try to manipulate your diet and lifestyle because you know that eventually you may end up being osteoporotic. So you probably have to take a higher calcium diet. Same thing with diabetes, you try to avoid sugar, carbohydrates and the like.”
However, it is more difficult to avoid psychiatric illness because of the ethical issues involved. “There is a very strong temptation to try to manipulate the genetic makeup since you know where the gene markers are and you have the ability to find out if you are predisposed to one illness or another,” Dr. Rosales remarked. “Of course this has received a lot of flak from many people because they say it’s unethical.”
He said that the idea of genetic markers in bipolar disease isn’t new because as early as 1987, it has been shown that there was already a genetic marker for mood disorders, particularly for bipolar disease. “You look at chromosome 11, you look at the short arm, you tickle the short arm…that’s where you will find the mutation that will eventually be implicated in bipolar disorder,” he said.
There are many genetic markers, a lot of which are still undiscovered, Dr. Rosales asserted. “Many genetic markers connected with the development of symptoms implicated bipolarity. Chances are, those associated with more than one psychiatric illness are not exclusive but don’t fret because it does not mean that you will develop the illness just by having a genetic marker.”
– Denn Meneses, Medical Observer