Evidence for Involvement of GNB1L in Autism

Department of Medicine (Medical Genetics), University of Washington, Seattle, Washington 98195-7720, USA.
American Journal of Medical Genetics Part B Neuropsychiatric Genetics (Impact Factor: 3.42). 01/2012; 159B(1):61-71. DOI: 10.1002/ajmg.b.32002
Source: PubMed


Structural variations in the chromosome 22q11.2 region mediated by nonallelic homologous recombination result in 22q11.2 deletion (del22q11.2) and 22q11.2 duplication (dup22q11.2) syndromes. The majority of del22q11.2 cases have facial and cardiac malformations, immunologic impairments, specific cognitive profile and increased risk for schizophrenia and autism spectrum disorders (ASDs). The phenotype of dup22q11.2 is frequently without physical features but includes the spectrum of neurocognitive abnormalities. Although there is substantial evidence that haploinsufficiency for TBX1 plays a role in the physical features of del22q11.2, it is not known which gene(s) in the critical 1.5 Mb region are responsible for the observed spectrum of behavioral phenotypes. We identified an individual with a balanced translocation 46,XY,t(1;22)(p36.1;q11.2) and a behavioral phenotype characterized by cognitive impairment, autism, and schizophrenia in the absence of congenital malformations. Using somatic cell hybrids and comparative genomic hybridization (CGH) we mapped the chromosome-22 breakpoint within intron 7 of the GNB1L gene. Copy number evaluations and direct DNA sequencing of GNB1L in 271 schizophrenia and 513 autism cases revealed dup22q11.2 in two families with autism and private GNB1L missense variants in conserved residues in three families (P = 0.036). The identified missense variants affect residues in the WD40 repeat domains and are predicted to have deleterious effects on the protein. Prior studies provided evidence that GNB1L may have a role in schizophrenia. Our findings support involvement of GNB1L in ASDs as well.

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    • "Similar to DISC1 in schizophrenia, several genes associated with ASD were also identified through mapping the breakpoints of chromosomal translocation found in patients with ASD. For example, ZF407 [Ren et al., 2013], GNB1L [Chen et al., 2012], and AUTS2 [Huang et al., 2010] were all identified from balanced translocation found in patients with autism. In this study, we identified a balanced reciprocal translocation t(4;14) (q31.3;q24.1) in a patient with ASD. "
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    ABSTRACT: Autism spectrum disorders (ASD) are childhood-onset neurodevelopmental disorders characterized by verbal communication impairments, social reciprocity deficits, and the presence of restricted interests and stereotyped behaviors. Genetic factors contribute to the incidence of ASD evidently. However, the genetic spectrum of ASD is highly heterogeneous. Chromosomal abnormalities contribute significantly to the genetic deficits of syndromic and non-syndromic ASD. In this study, we conducted karyotyping analysis in a sample of 500 patients (447 males, 53 females) with ASD from Taiwan, the largest cohort in Asia, to the best of our knowledge. We found three patients having sex chromosome aneuploidy, including two cases of 47, XXY and one case of 47, XYY. In addition, we detected a novel reciprocal chromosomal translocation between long arms of chromosomes 4 and 14, designated t(4;14)(q31.3;q24.1), in a patient with Asperger's disorder. This translocation was inherited from his unaffected father, suggesting it might not be pathogenic or it needs further hits to become pathogenic. In line with other studies, our study revealed that subjects with sex chromosomal aneuploidy are liable to neurodevelopmental disorders, including ASD, and conventional karyotyping analysis is still a useful tool in detecting chromosomal translocation in patients with ASD, given that array-based comparative genomic hybridization technology can provide better resolution in detecting copy number variations of genomic DNA. © 2013 Wiley Periodicals, Inc.
    Full-text · Article · Oct 2013 · American Journal of Medical Genetics Part B Neuropsychiatric Genetics
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    • "Direct evidence regarding this hypothesis comes from Addington and Rapoport [109], who showed that individuals with childhood-onset schizophrenia mediated by schizophrenia-associated CNVs were more likely to exhibit premorbidity to schizophrenia in the form of developmental delays (p = 0.0001) and may have been more likely to exhibit diagnoses of a PDD (p = 0.10) compared to such children lacking these CNVs. Additional evidence comes from studies by Ingason et al. [7] and Chen et al. [110], who each reported sequential diagnoses of autism spectrum disorder in childhood and schizophrenia in adulthood among an individual with such alterations (respectively, a duplication of 15q11-q13 and a balanced translocation disrupting GNB1L, a gene in the 22q11.2 deletion region). "
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    ABSTRACT: Autism spectrum disorders and schizophrenia have been associated with an overlapping set of copy number variant loci, but the nature and degree of overlap in copy number variants (deletions compared to duplications) between these two disorders remains unclear. We systematically evaluated three lines of evidence: (1) the statistical bases for associations of autism spectrum disorders and schizophrenia with a set of the primary CNVs thus far investigated, from previous studies; (2) data from case series studies on the occurrence of these CNVs in autism spectrum disorders, especially among children, and (3) data on the extent to which the CNVs were associated with intellectual disability and developmental, speech, or language delays. We also conducted new analyses of existing data on these CNVs in autism by pooling data from seven case control studies. Four of the CNVs considered, dup 1q21.1, dup 15q11-q13, del 16p11.2, and dup 22q11.21, showed clear statistical evidence as autism risk factors, whereas eight CNVs, del 1q21.1, del 3q29, del 15q11.2, del 15q13.3, dup 16p11.2, dup 16p13.1, del 17p12, and del 22q11.21, were strongly statistically supported as risk factors for schizophrenia. Three of the CNVs, dup 1q21.1, dup 16p11.2, and dup 16p13.1, exhibited statistical support as risk factors for both autism and schizophrenia, although for each of these CNVs statistical significance was nominal for tests involving one of the two disorders. For the CNVs that were statistically associated with schizophrenia but were not statistically associated with autism, a notable number of children with the CNVs have been diagnosed with autism or ASD; children with these CNVs also demonstrate a high incidence of intellectual disability and developmental, speech, or language delays. These findings suggest that although CNV loci notably overlap between autism and schizophrenia, the degree of strongly statistically supported overlap in specific CNVs at these loci remains limited. These analyses also suggest that relatively severe premorbidity to CNV-associated schizophrenia in children may sometimes be diagnosed as autism spectrum disorder.
    Full-text · Article · May 2012 · Journal of Neurodevelopmental Disorders
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    ABSTRACT: Over the past several decades, progress in understanding the genetic basis of autism spectrum disorder (ASD) has dramatically altered our conception of its genetic architecture. Once believed to be an oligogenic disorder of common susceptibility variants, autism is now considered to be a collection of distinct 'autisms marked by profound genetic heterogeneity. While twin and family studies have demonstrated a strong genetic etiology, genome-wide linkage and association studies have been limited by the extreme underlying heterogeneity. Genome-wide association studies have identified a few variants with small effects on ASD risk, but no common variants that clearly explain the few replicated linkage signals have been identified, suggesting that common variation is unlikely to play a central role. Recent successes in characterizing genetic risk have been driven by technological advances permitting the identification of de novo variants, both single-nucleotide variants and copy number variants, occurring in sporadic autism. The power to detect modest, rare inherited effects has been achieved through growing sample sizes through large collaborations; however, the inherited risk of ASD remains largely uncharted. Several hundred risk genes for ASD have been proposed, many linked via shared physiologic pathways. While many investigators now estimate that the number of autism risk genes will reach the thousands, pathway analysis will facilitate the understanding of ASD pathophysiology, the identification of novel risk genes and the development of clinically actionable targets. Molecular diagnosis has become possible for many ASD subtypes and will continue to expand. Targeted interventions will be developed and individualized based on diagnostic data and the growing appreciation of the biology of autism.
    No preview · Article · Apr 2013
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