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Schizophrenia is a devastating neurodevelopmental disorder whose genetic influences remain elusive. We hypothesize that individually rare structural variants contribute to the illness. Microdeletions and microduplications >100 kilobases were identified by microarray comparative genomic hybridization of genomic DNA from 150 individuals with schizophrenia and 268 ancestry-matched controls. All variants were validated by high-resolution platforms. Novel deletions and duplications of genes were present in 5% of controls versus 15% of cases and 20% of young-onset cases, both highly significant differences. The association was independently replicated in patients with childhood-onset schizophrenia as compared with their parents. Mutations in cases disrupted genes disproportionately from signaling networks controlling neurodevelopment, including neuregulin and glutamate pathways. These results suggest that multiple, individually rare mutations altering genes in neurodevelopmental pathways contribute to schizophrenia.

Individuals with autism are more likely to carry rare inherited and de novo copy number variants (CNVs). However, further research is needed to establish which CNVs are causal and the mechanisms by which these CNVs influence autism. We examined genomic DNA of children with autism ( N =41) and healthy controls ( N =367) for rare CNVs using a high-resolution array comparative genomic hybridization platform. We show that individuals with autism are more likely to harbor rare CNVs as small as ∼10 kb, a threshold not previously detectable, and that CNVs in cases disproportionately affect genes involved in transcription, nervous system development, and receptor activity. We also show that a subset of genes that have known or suspected allele-specific or imprinting effects and are within rare-case CNVs may undergo loss of transcript expression. In particular, expression of CNTNAP2 and ZNF214 are decreased in probands compared with their unaffected transmitting parents. Furthermore, expression of PRODH and ARID1B , two genes affected by de novo CNVs, are decreased in probands compared with controls. These results suggest that for some genes affected by CNVs in autism, reduced transcript expression may be a mechanism of pathogenesis during neurodevelopment.

Schizophrenia is widely held to stem from the combined effects of multiple common polymorphisms, each with a small impact on disease risk. We suggest an alternative view: that schizophrenia is highly heterogeneous genetically and that many predisposing mutations are highly penetrant and individually rare, even specific to single cases or families. This ‘common disease – rare alleles' hypothesis is supported by recent findings in human genomics and by allelic and locus heterogeneity for other complex traits. We review the implications of this model for gene discovery research in schizophrenia.

RING1 is an E3-ubiquitin ligase that is involved in epigenetic control of transcription during development. It is a component of the polycomb repressive complex 1, and its role in that complex is to ubiquitylate histone H2A. In a 13-year-old girl with syndromic neurodevelopmental disabilities, we identified a de novo mutation, RING1 p.R95Q, which alters a conserved arginine residue in the catalytic RING domain. In vitro assays demonstrated that the mutant RING1 retains capacity to catalyze ubiquitin chain formation, but is defective in its ability to ubiquitylate histone H2A in nucleosomes. Consistent with this in vitro effect, cells of the patient showed decreased monoubiquitylation of histone H2A. We modeled the mutant RING1 in Caenorhabditis elegans by editing the comparable amino acid change into spat-3, the suggested RING1 ortholog. Animals with either the missense mutation or complete knockout of spat-3 were defective in monoubiquitylation of histone H2A and had defects in neuronal migration and axon guidance. Relevant to our patient, animals heterozygous for either the missense or knockout allele also showed neuronal defects. Our results support three conclusions: mutation of RING1 is the likely cause of a human neurodevelopmental syndrome, mutation of RING1 can disrupt histone H2A ubiquitylation without disrupting RING1 catalytic activity, and the comparable mutation in C. elegans spat-3 both recapitulates the effects on histone H2A ubiquitylation and leads to neurodevelopmental abnormalities. This role for RING1 adds to our understanding of the importance of aberrant epigenetic effects as causes of human neurodevelopmental disorders.

(2017) raise two critical needs: (1) the identification of factors that predict whether (and for which youth) prescribed medications will significantly improve long-term functioning, including social, academic, and mental health outcomes and (2) the need to incorporate systematic medication monitoring into routine clinical practice. The potential risk of cardiovascular side effects with stimulant medications supports the need for systematic monitoring of heart rate and blood pressure; routine assessment of medical problems and family medical history; and adequate informed consent. [...]the behavioral improvements noted with stimulant medications are not unique to children with attention-deficit/hyperactivity disorder (ADHD), and are found in those with other conditions, as well as in normal children (Rapoport and Inoff-Germain 2002). Intervention research and development must focus on improving long-term outcomes that matter most, for example, ameliorating morbidity and mortality, enhancing academic achievement and economic independence, and reducing the risk of suicide, criminality, substance abuse, violence, and child maltreatment.

Schizophrenia is widely held to stem from the combined effects of multiplecommon polymorphisms, each with a small impact on disease risk. We suggestan alternative view: that schizophrenia is highly heterogeneous geneticallyand that many predisposing mutations are highly penetrant and individuallyrare, even specific to single cases or families. This ‘common disease – rarealleles' hypothesis is supported by recent findings in human genomics and byallelic and locus heterogeneity for other complex traits. We review theimplications of this model for gene discovery research in schizophrenia.