Research interests and plans
My research interests focus on genetic epidemiology of psychiatric and neurological disorders concentrating on Obsessive Compulsive Disorder (OCD) and various epilepsy syndromes. These disorders of complex etiology require a multidisciplined approach, challenging one to incorporate clinical knowledge into the analyses.
Obsessive-Compulsive Disorder (OCD) is characterized by obsessions (intrusive and persistent ideas or thoughts) and compulsions (senseless, repetitive purposeful behaviors) which interfere with normal functioning.. My lab is interested in studying the mode of inheritance of OCD and the effect of other psychiatric disorders that can co-occur with OCD. My interest in the genetics of psychiatric disorders began during my Medical Genetics postdoctoral fellowship at the University of California, Los Angeles (UCLA). There I performed a linkage analysis of a large pedigree in which Obsessive-Compulsive Disorder (OCD) appeared to be transmitted in a dominant pattern. We found some evidence of linkage to chromosome 4. Also while at UCLA, I collaborated on a segregation analysis of 24 families ascertained through a single child proband with OCD. This study, although small, was the first to provided evidence of single gene effects in the etiology OCD.
We are currently analyzing data obtained from a family study of OCD. OCD patients and their families have been ascertained through Tulane University Department of Psychiatry and Neurology and the Instituto Mexicano de Psiquiatría though our collaboration with Dr. Humberto Nicolini in Mexico City. The Mexican site has provided us with data from 75 Mexican OCD patients. We are in the process of performing complex segregation analyses on these data. Preliminary results suggest evidence for a dominantly acting gene affecting OCD suceptibility. Also in collaboration with Dr. Nicolini, we performed an association study in which we compared the allele and genotype frequencies of polymorphisms at three dopamine receptor genes and a seratonin gene in a group of 67 OCD patients to the frequencies found among 54 healthy controls. There were no statistically significant differences between the two groups for any of the polymorphisms, however, when the OCD patients were divided based on the presence or absence of vocal or motor tics, the group with tics had a greater degree of homozygosity for one allele of the DRD2 gene. These findings suggest that OCD patients with tics may represent a genetic subgroup of the disease.
We are also interested in the relationship between OCD and other psychiatric disorders. In collaboration with Dr. Mark Townsend at Louisiana State University Medical Center, we recently completed a small study in which we compared the compulsion sub-scale of the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) of 26 OCD patients, 23 patients with Generalize Anxiety Disorder (GAD) and 24 subjects with no psychiatric diagnosis. Our results suggested that checking behaviors, while lacking functional impairment associated with OCD, also occur in individuals with GAD, and that GAD might be considered as part of the OCD spectrum. We hope to continue our OCD research by studying the role of obsessive- compulsive symptoms in other disorders such as Anorexia Nervosa and by beginning a search for genes which may contribute to the susceptibility of OCD.