Obsessive-compulsive disorder (OCD) is a psychiatric condition characterized by intrusive thoughts and urges and repetitive, intentional behaviors that cause significant distress and impair functioning. The OCD Collaborative Genetics Association Study (OCGAS) is comprised of comprehensively assessed OCD patients, with an early age of OCD onset. After application of a stringent quality control protocol, a total of 1 065 families (containing 1 406 patients with OCD), combined with population-based samples (resulting in a total sample of 5 061 individuals), were studied. An integrative analyses pipeline was utilized, involving association testing at SNP- and gene-levels (via a hybrid approach that allowed for combined analyses of the family- and population-based data). The smallest P-value was observed for a marker on chromosome 9 (near PTPRD, P=4.13×10−7). Pre-synaptic PTPRD promotes the differentiation of glutamatergic synapses and interacts with SLITRK3. Together, both proteins selectively regulate the development of inhibitory GABAergic synapses. Although no SNPs were identified as associated with OCD at genome-wide significance level, follow-up analyses of GWAS signals from a previously published OCD study identified significant enrichment (P=0.0176). Secondary analyses of high confidence interaction partners of DLGAP1 and GRIK2 (both showing evidence for association in our follow-up and the original GWAS study) revealed a trend of association (P=0.075) for a set of genes such as NEUROD6, SV2A, GRIA4, SLC1A2, and PTPRD. Analyses at the gene-level revealed association of IQCK and C16orf88 (both P<1×10−6, experiment-wide significant), as well as OFCC1 (P=6.29×10−5). The suggestive findings in this study await replication in larger samples.

BackgroundLittle is known about personality disorders and normal personality dimensions in relatives of patients with obsessive-compulsive disorder (OCD).AimsTo determine whether specific personality characteristics are part of a familial spectrum of OCD.MethodClinicians evaluated personality disorders in 72 OCD case and 72 control probands and 198 case and 207 control first-degree relatives. The self-completed Revised NEO Personality Inventory was used for assessment of normal personality dimensions. The prevalence of personality disorders and scores on normal personality dimensions were compared between case and control probands and between case and control relatives.ResultsCase probands and case relatives had a high prevalence of obsessive-compulsive personality disorder (OCPD) and high neuroticism scores. Neuroticism was associated with OCPD in case but not control relatives.ConclusionsNeuroticism and OCPD may share a common familial aetiology with OCD.

Obsessive-compulsive disorder (OCD) is the tenth most disabling medical condition worldwide. Twin and family studies implicate a genetic etiology for this disorder, although specific genes have yet to be identified. Here, we present the first large-scale model-free linkage analysis of both extended and nuclear families using both 'broad' (definite and probable diagnoses) and 'narrow' (definite only) definitions of OCD. We conducted a genome-scan analysis of 219 families collected as part of the OCD Collaborative Genetics Study. Suggestive linkage signals were revealed by multipoint analysis on chromosomes 3q27-28 (P = 0.0003), 6q (P = 0.003), 7p (P = 0.001), 1q (P = 0.003), and 15q (P = 0.006). Using the 'broad' OCD definition, we observed the strongest evidence for linkage on chromosome 3q27-28. The maximum overall Kong and Cox LOD all score (2.67) occurred at D3S1262 and D3S2398, and simulation based P-values for these two signals were 0.0003 and 0.0004, respectively, although for both signals, the simulation-based genome-wide significance levels were 0.055. Covariate-linkage analyses implicated a possible role of gene(s) on chromosome 1 in increasing the risk for an earlier onset form of OCD. We are currently pursuing fine mapping in the five regions giving suggestive signals, with a particular focus on 3q27-28. Given probable etiologic heterogeneity in OCD, mapping gene(s) involved in the disorder may be enhanced by replication studies, large-scale family-based linkage studies, and the application of novel statistical methods.

A robust approach for estimating standard errors of variance components by using quantitative phenotypes from families ascertained through a proband with an extreme phenotypic value is presented. Estimators that use the multivariate normal distribution as a "working likelihood" are obtained by computing conditional ln-likelihoods, conditional first and second derivatives in a Newton-Raphson approach. Robust estimates of standard errors about the estimators are also provided. Tests of hypotheses are based on a modification of the score test, which allows the assumption of multivariate normality to be relaxed. Conditional goodness-of-fit statistics are proposed that can be used to examine the fit of separate pedigrees to the overall model. This robust approach for estimating the standard errors for variance components by conditioning on the proband's phenotype will allow general inferences to be made from the analysis of families ascertained through probands with extreme or unusual phenotypes and should be most appropriate for studying many physiological traits that may be intrinsically nonnormal.