These preliminary findings suggest that stimulation of the subthalamic nucleus may reduce the symptoms of severe forms of OCD but is associated with a substantial risk of serious adverse events. (ClinicalTrials.gov number, NCT00169377.)

Despite a lack of recent progress in the treatment of schizophrenia, our understanding of its genetic and environmental causes has considerably improved, and their relationship to aberrant patterns of neurodevelopment has become clearer. This raises the possibility that 'disease-modifying' strategies could alter the course to - and of - this debilitating disorder, rather than simply alleviating symptoms. A promising window for course-altering intervention is around the time of the first episode of psychosis, especially in young people at risk of transition to schizophrenia. Indeed, studies performed in both individuals at risk of developing schizophrenia and rodent models for schizophrenia suggest that pre-diagnostic pharmacotherapy and psychosocial or cognitive-behavioural interventions can delay or moderate the emergence of psychosis. Of particular interest are 'hybrid' strategies that both relieve presenting symptoms and reduce the risk of transition to schizophrenia or another psychiatric disorder. This Review aims to provide a broad-based consideration of the challenges and opportunities inherent in efforts to alter the course of schizophrenia.

Genome Biology 2011, 12(Suppl 1):I18 Deep exome resequencing is a powerful approach for delineating patterns of protein-coding variation among genes, pathways, individuals and populations. We analyzed exome data from 2,440 individuals of European and African ancestry as part of the National Heart, Lung, and Blood Institute's Exome Project, the aim of which is to discover novel genes and mechanisms that contribute to heart, lung and blood disorders. Each exome was sequenced to a mean coverage of 116×, allowing detailed inferences about the population genomic patterns of both common variation and rare coding variation. We identifi ed more than 500,000 single nucleotide variations, the majority of which were novel and rare (76% of variants had a minor allele frequency of less than 0.1%), refl ecting the recent dramatic increase in the size of the human population. The unprecedented magnitude of this dataset allowed us to rigorously characterize the large variation in nucleotide diversity among genes (ranging from 0 to 1.32%), as well as the role of positive and purifying selection in shaping patterns of protein-coding variation and the diff erential signatures of population structure from rare and common variation. This dataset provides a framework for personal genomics and is an important resource that will allow inferences of broad importance to human evolution and health. I2 Abstract not submitted for online publication. I3 Are clinical genomes already becoming semi-routine for patient care?

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Schizophrenia likely results from poorly understood genetic and environmental factors. We studied the gene encoding the synaptic protein SHANK3 in 285 controls and 185 schizophrenia patients with unaffected parents. Two de novo mutations (R1117X and R536W) were identified in two families, one being found in three affected brothers, suggesting germline mosaicism. Zebrafish and rat hippocampal neuron assays revealed behavior and differentiation defects resulting from the R1117X mutant. As mutations in SHANK3 were previously reported in autism, the occurrence of SHANK3 mutations in subjects with a schizophrenia phenotype suggests a molecular genetic link between these two neurodevelopmental disorders. S chizophrenia (SCZ) is a chronic psychiatric disorder characterized by a profound disruption in cognition, behavior, and emotion which begins in adolescence or early adulthood. There is significant clinical variability among SCZ patients, suggesting that it is etiologically heterogeneous. There are several hypotheses to explain genetic factors underlying SCZ, such as polygenic inheritance (1) or, in a fraction of cases, variably penetrant de novo mutations. The de novo hypothesis is based on several observations. One is that relatives of an individual with SCZ have a higher risk of being affected (parents 6%, offspring 13%, and siblings 9% compared with 1% for the general population) (2). The greater frequency in offspring than in parents may occur if new mutations account for a fraction of SCZ cases. Also, there is a significantly increased risk of SCZ with increasing paternal age (3), which could result from the age-related increase in paternal de novo mutations. Furthermore, despite reduced reproductive fitness (4) and extremely variable environmental factors, the incidence of SCZ is maintained at ∼1% worldwide. Interestingly, recent studies reported de novo copy-number variants in SCZ, providing further support for the de novo mutation hypothesis (5, 6).As part of the Synapse to Disease (S2D) project aimed at exploring the de novo mutation hypothesis in brain diseases, we are sequencing synaptic genes in individuals with SCZ and autism spectrum disorder (ASD), two neurodevelopmental disorders. Recently, mutations in the SHANK3 (SH3 and multiple ankyrin repeat domains 3) gene, encoding a scaffolding protein abundant in the postsynaptic density of excitatory synapses on dendritic spines, were found in patients with ASD (7-9). Considering that ASD and SCZ share some features, we decided to screen the SHANK3 gene in our cohort of SCZ probands. Given our hypothesis that a significant fraction of SCZ cases are the result of new mutations, we selected SCZ cases with unaffected parents and screened for de novo mutations.

Autism spectrum disorder (ASD) and schizophrenia (SCZ) are two common neurodevelopmental syndromes that result from the combined effects of environmental and genetic factors. We set out to test the hypothesis that rare variants in many different genes, including de novo variants, could predispose to these conditions in a fraction of cases. In addition, for both disorders, males are either more significantly or more severely affected than females, which may be explained in part by X-linked genetic factors. Therefore, we directly sequenced 111 X-linked synaptic genes in individuals with ASD (n = 142; 122 males and 20 females) or SCZ (n = 143; 95 males and 48 females). We identified > 200 non-synonymous variants, with an excess of rare damaging variants, which suggest the presence of disease-causing mutations. Truncating mutations in genes encoding the calcium-related protein IL1RAPL1 (already described in Piton et al. Hum Mol Genet 2008) and the monoamine degradation enzyme monoamine oxidase B were found in ASD and SCZ, respectively. Moreover, several promising non-synonymous rare variants were identified in genes encoding proteins involved in regulation of neurite outgrowth and other various synaptic functions (MECP2, TM4SF2/TSPAN7, PPP1R3F, PSMD10, MCF2, SLITRK2, GPRASP2, and OPHN1).

Engrailed1 and Engrailed2 (En1 and En2) are two developmental genes of the homeogene family expressed in the developing midbrain. En1 and, to a lesser degree, En2 also are expressed in the adult substantia nigra (SN) and ventral tegmental area (VTA), two dopaminergic (DA) nuclei of the ventral midbrain. In an effort to study En1/2 adult functions, we have analyzed the phenotype of mice lacking one En1 allele in an En2 wild-type context. We show that in this mutant the number of DA neurons decreases slowly between 8 and 24 weeks after birth to reach a stable 38 and 23% reduction in the SN and VTA, respectively, and that neuronal loss can be antagonized by En2 recombinant protein infusions in the midbrain. These loss and gain of function experiments firmly establish that En1/2 is a true survival factor for DA neurons in vivo. Neuronal death in the mutant is paralleled by a 37% decrease in striatal DA, with no change in serotonin content. Using established protocols, we show that, compared with their wild-type littermates, En1ϩ/Ϫ mice have impaired motor skills, an anhedonic-like behavior, and an enhanced resignation phenotype; they perform poorly in social interactions. However, these mice do not differ from their wild-type littermates in anxiety-measuring tests. Together, these results demonstrate that En1/2 genes have important adult physiological functions. They also suggest that mice lacking only one En1 allele could provide a novel model for the study of diseases associated with progressive DA cell death.