Genetic Associations of Serotoninergic and GABAergic Genes in an Extended Collection of Early-Onset Obsessive-Compulsive Disorder Trios

Correlations between single nucleotide polymorphisms in obsessive-compulsive disorder with the clinical features or response to therapy

Obsessive-compulsive disorder (OCD) is a debilitating neuropsychiatric disorder, in which the patient endures intrusive thoughts or is compelled to perform repetitive or ritualized actions. Many cases of OCD are considered to be familial or heritable in nature. It has been shown that a variety of internal and external risk factors are involved in the pathogenesis of OCD. Among the internal factors, genetic modifications play a critical role in the pathophysiological process. Despite many investigations performed to determine the candidate genes, the precise genetic factors involved in the disease remain largely undetermined. The present review summarizes the single nucleotide polymorphisms that have been proposed to be associated with OCD symptoms, early onset disease, neuroimaging results, and response to therapy. This information could help us to draw connections between genetics and OCD symptoms, better characterize OCD in individual patients, understand OCD prognosis, and design more targeted personalized treatment approaches.

Early onset obsessive-compulsive disorder: the biological and clinical phenotype

Moving from a behavioral-based to a biological-based classification of mental disorders is a crucial step toward a precision-medicine approach in psychiatry. In the last decade, a big effort has been made in order to stratify genetic, immunological, neurobiological, cognitive, and clinical profiles of patients. Making the case of obsessive-compulsive disorder (OCD), a lot have been made in this direction. Indeed, while the Diagnostic and Statistical Manual of Mental Disorders (DSM) diagnosis of OCD aimed to delineate a homogeneous group of patients, it is now clear that OCD is instead an heterogeneous disorders both in terms of neural networks, immunological, genetic, and clinical profiles. In this view, a convergent amount of literature, in the last years, indicated that OCD patients with an early age at onset seem to have a specific clinical and biological profile, suggesting it as a neurodevelopmental disorder. Also, these patients tend to have a worse outcome respect to adult-onset patients and there is growing evidence that early-interventions could potentially improve their prognosis. Therefore, the aim of the present paper is to review the current available genetic, immunological, neurobiological, cognitive, and clinical data in favor of a more biologically precise subtype of OCD: the early-onset subtype. We also briefly resume current available recommendations for the clinical management of this specific population.

Cannabis Improves Obsessive-Compulsive Disorder-Case Report and Review of the Literature

Although several lines of evidence support the hypothesis of a dysregulation of serotoninergic neurotransmission in the pathophysiology of obsessive-compulsive disorder (OCD), there is also evidence for an involvement of other pathways such as the GABAergic, glutamatergic, and dopaminergic systems. Only recently, data obtained from a small number of animal studies alternatively suggested an involvement of the endocannabinoid system in the pathophysiology of OCD reporting beneficial effects in OCD-like behavior after use of substances that stimulate the endocannabinoid system. In humans, until today, only two case reports are available reporting successful treatment with dronabinol (tetrahydrocannabinol, THC), an agonist at central cannabinoid CB1 receptors, in patients with otherwise treatment refractory OCD. In addition, data obtained from a small open uncontrolled trial using the THC analogue nabilone suggest that the combination of nabilone plus exposure-based psychotherapy is more effective than each treatment alone. These reports are in line with data from a limited number of case studies and small controlled trials in patients with Tourette syndrome (TS), a chronic motor and vocal tic disorder often associated with comorbid obsessive compulsive behavior (OCB), reporting not only an improvement of tics, but also of comorbid OCB after use of different kinds of cannabis-based medicines including THC, cannabis extracts, and flowers. Here we present the case of a 22-year-old male patient, who suffered from severe OCD since childhood and significantly improved after treatment with medicinal cannabis with markedly reduced OCD and depression resulting in a considerable improvement of quality of life. In addition, we give a review of current literature on the effects of cannabinoids in animal models and patients with OCD and suggest a cannabinoid hypothesis of OCD.

Is there a correlation between GAD2 gene-243 A>G polymorphism and obesity?

Introduction: GAD2 gene encodes the glutamate decarboxylase enzyme which catalyses the transformation of glutamate into γ-aminobutyric acid, GABA. It is suggested that some polymorphic alleles of GAD2 gene, such as -243A>G, have an increased transcriptional effect compared with the wild type, which results in an increase of GABA in the hypothalamus with the subsequent increase of the neuropeptide Y, thus exacerbating the hunger centre and the appetite. The aim of this study was to observe an association between the -243A>G polymorphism with obesity, comparatively studying a group of obese patients and a group of patients with normal weight.

Patients and method: 127 patients were clinically evaluated in the Genetic and Endocrine Department of Children’s Emergency Clinical Hospital, Cluj. The patients were included in two study groups, case group, with obesity (BMI higher than 97 kg/m2) and control group, with normal weight (BMI less than 97 kg/m2). Genotyping for GAD2-243A>G polymorphism was performed using PCR-RFLP technique, the two groups being compared regarding the genotypes and phenotypes.

Results and conclusions: In the obesity group, there is a statistically significant difference in BMI (kg/m2) between the subgroups with different genotypes (p=0.01), the AA genotype being less severely affected than AG and GG genotypes. In the normal weight group there is no association between BMI and different genotypes (AA, AG or GG). Also, there is a greater distribution of GG genotypes and G allele in the obesity group compared with the control group, with an odds ratio which suggest that -243A>G polymorphism is a risk factor in obesity development (GG genotype OR=3.76, G allele OR=1.73, p=0.04).

The finding of our study is important in explaining the multifactorial model of obesity, our research demonstrating that the GAD2-243 A> G variant could be a risk factor that added to other obesogenic factors would potentiate their effect.