Doc, I saw on the news that a gene for schizophrenia has been found. Can I be tested for it?" Such inquiries from patients with psychiatric disorders and their at-risk family members are increasing as knowledge about the genetic basis of psychiatric illness grows, according to Harvard Medical School experts in genetics and psychiatric disorders.
In a recent article on genetic counseling in psychiatry,1 Christine Finn, MD, and Jordan W. Smoller, MD, ScD, noted that family and twin studies have documented the familiality and heritability of schizophrenia, bipolar disorder, major depression, anxiety disorders, autism, attention-deficit/hyperactivity disorder (ADHD), and Tourette syndrome, among others, and that molecular genetic studies have begun to identify possible susceptibility loci for several of these disorders, most notably schizophrenia.
"Right now, the clinical applications of genetics to psychiatry are relatively small," Finn told Psychiatric Times, "but I think that is going to change dramatically in a relatively short time as we are able to identify genes that may be important for the development of psychiatric disorders or that may be important for gauging responses to medications or even other forms of treatment."
Finn, who is board certified in both psychiatry and genetics, warned that there may not be enough trained genetics professionals to handle the increasing demand for genetic counseling and testing. What's more, she said, genetic counselors currently do not get much exposure to psychiatry.
"Inevitably," she added, "it is going to fall on primary care physicians and other specialties, like psychiatry, to have some facility with genetic information and to be able to use that [information] in their clinical practice to really give patients the highest standard of care."
Unfortunately, genetics and genetic counseling "is not something that a lot of psychiatrists know much about," Finn said. In a survey of 352 psychiatrists, respondents had a median score of 44% on the general genetic knowledge items and 33% on the psychiatric genetic knowledge items.2 In particular, the surveyed psychiatrists tended to underestimate the genetic contribution to schizophrenia, autism, Alzheimer disease, and ADHD. Despite their knowledge gaps, 83% of the psychiatrists considered it their role to discuss genetic information with patients and families.
The need is great and growing. American Psychiatric Association (APA) guidelines have endorsed genetic counseling to aid family planning for individuals with bipolar disorder; the APA also indicated that when genetic counseling is used in the psychiatric evaluation of adults, the relevance of patients' value systems should be taken into consideration.
Genetic information also can guide treatment. For example, a patient undergoing a first episode of depression whose close relatives have bipolar disorder may be better off starting with a mood stabilizer rather than a standard antidepressant.
Disorders for which genetic testing may be valuable
Already available, Finn said, is genetic testing for several highly penetrant single-gene or chromosomal abnormalities that can cause psychiatric symptoms.
"The one I am most familiar with and most interested in is velocardiofacial/DiGeorge syndrome [VCFS]," she said. "It is relatively common as genetic disorders go. Other than Down syndrome, it is probably the most common genetic syndrome that we know about. Down syndrome occurs, on average, in about 1 in 700, and [VCFS] occurs, depending on what you read, in between 1 in 2000 and 1 in 4000 live births."
1. Finn CT, Smoller JW. Genetic counseling in psychiatry. Harv Rev Psychiatry. 2006;14:109-121.
2. Finn CT, Wilcox A, Korf BR, et al. Psychiatric genetics: a survey of psychiatrists' knowledge, opinions, and practice patterns. J Clin Psychiatry. 2005:66:821-830.
3. Gothelf D, Lombroso PJ. Genetics of childhood disorders, XXV: velocardiofacial syndrome. J Am Acad Child Adolesc Psychiatry. 2001;40:489-491.