Unknown,Transcriptomics,Genomics,Proteomics

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Comparative genomic hybridization suggests a role for NRXN1 and APBA2 in schizophrenia

ABSTRACT: Copy number variations (CNVs) account for a substantial proportion of human genomic variation, and have been shown to cause neurodevelopmental disorders. We sought to determine the relevance of CNVs to the aetiology of schizophrenia. Whole genome, high resolution, tiling path BAC array comparative genomic hybridization (array CGH) was employed to test DNA from 91 individuals with DSM-IV schizophrenia. Common DNA copy number changes that are unlikely to be directly pathogenic in schizophrenia were identified by comparison to a reference dataset of 372 control individuals analysed in our laboratory, and a screen against the Database of Genomic Variants. The remaining aberrations were tested for inheritance from the parents, and validated with Affymetrix 250K SNP arrays or 244K Agilent oligo-arrays. Thirteen aberrations satisfied our criteria. Two of them are very likely to be pathogenic. A deletion at 2p16.3 disrupts NRXN1 and was present in an affected sibling. A de novo duplication at 15q13.1 spans APBA2. The proteins of these two genes interact directly and play a role in synaptic development and function. Both genes have been affected by CNVs in other neurodevelopmental disorders. Keywords: Array CGH We undertook a systematic search for CNVs in patients with schizophrenia using high resolution, whole genome tiling path BAC arrays. We selected 45 male and 48 female unrelated proband-parent trios from our sample of ~600 Bulgarian SZ trios recruited as described previously. In all cases IQ was > 70. The mean age of probands was 33.8 years (SD = 10.1, range 13-57 years). The mean age at onset of psychotic symptoms was 22.1 years (SD = 6.6, range 11-44 years). Sonicated patient and reference DNA was labelled by random priming (Bioprime Array CGH, Invitrogen, Carlsbad, CA) with Cy3 and Cy5 (Amersham Biosciences, Piscataway, NJ), respectively, and hybridized onto a tiling path BAC array, consisting of ~36,000 BAC clones obtained from several sources as described on our website (http://www.molgen.mpg.de/~abt_rop/molecular_cytogenetics/). All protocols are also provided on that website. For the analysis and visualization of array CGH data, our software-package CGHPRO was employed. For the assessment of copy number gains and losses, we used conservative log2 ratio thresholds of 0.3 and -0.3, respectively. Deviant signal intensity ratios involving three or more neighboring BAC clones were considered to be potentially pathogenic, unless they were covered by more than one known DNA copy number variant, as listed in the Database of Genomic Variants. No dye swap was done. Array CGH analysis was successful in 91 cases.

ORGANISM(S): Homo sapiens

SUBMITTER: Reinhard Ullmann

PROVIDER: E-GEOD-8606 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Congenital Hypothyroidism occurs in 1:3500 live births and is therefore the most common congenital endocrine disorder. A spectrum of defective thyroid morphology, termed thyroid dysgenesis, represents 80% of permanent CH cases. Although several candidate genes have been implicated in thyroid development, comprehensive screens failed to detect mutation carriers in a significant number of patients with non-syndromic TD. Due to the sporadic occurrence of TD, de novo chromosomal rearrangements are conceivably representing one of the molecular mechanisms participating in its aetiology. Recently, the use of array CGH technique has provided the ability to map these variations genomewide with high resolution. We performed an array CGH screen of 74 TD patients to determine the role of copy number variants (CNV) in the aetiology of the disease. We identified novel CNVs in 8.75% of all patients that have not been described as frequent variations in the healthy population. Affected patients presented with athyreosis or thyroid hypoplasia and in one case with associated heart malformation. We selected 74 patients with thyroid dysgenesis for array CGH analysis. All individuals were detected in neonatal screening programs and abnormal thyroid gland morphology was subsequently confirmed by ultrasound examination. Intragenic mutations in NKX2-1, FOXE1 and NKX2.5 had been previously excluded in phenotype characteristic individuals. PAX8 mutations were excluded in all patients with hypoplastic thyroids by direct sequencing of the coding exons 1-11. The study was approved by the local ethics committee. Genomic DNA of all subjects as well as of healthy controls was isolated from peripheral blood leucocytes using the Qiagen DNA blood mini kit (Qiagen, Hilden, Germany). Array-comparative genomic hybridization was carried as described previously {Erdogan, 2006 #142; Pinkel, 1998 #151}. In brief, sonicated patient- and control DNA was labeled by random priming with Cy3-dUTP and Cy5-dUTP (Bioprime Array CGH, Invitrogen, Carlsbad, CA), respectively, and hybridized onto a submegabase resolution tiling path BAC array, consisting of ~ 36 000 BAC clones obtained from several sources as described elsewhere {Fiegler, 2003 #198; Ishkanian, 2004 #196; Krzywinski, 2004 #197} . Step-by-step protocols are also provided at http://www.molgen.mpg.de/~abt_rop/molecular_cytogenetics/. Arrays were scanned with the G2565BA Agilent Microarray Scanner System (resolution 10 µm; PMT 100 % for Cy3/Cy5, respectively) (Agilent Inc. Santa Clara, CA) and analyzed using GENEPIX Pro 5.0 Software. Analysis and visualization of array CGH data were performed with our software package CGHPRO {Chen, 2005 #143}. For the assessment of copy number gains and losses, we used conservative log2 ratio thresholds of 0.3 and -0.3, respectively. Deviant signal intensity ratios involving three or more consecutive BAC clones were considered to be potentially pathogenic, unless they were covered by more than one known DNA copy number variant, as listed in the Database of Genomic Variants (http://projects.tcag.ca/variation/) or covered by > 50% of their length at least once in our reference set of 600 samples. Potentially pathogenic CNVs were verified by array CGH on a 244k oligonucleotide array from Agilent following the manufacturer’s instructions (Protocol-No. G4410-90010). Confirmed CNVs were tested for inheritance by co-hybridization of parental DNA on BAC arrays as described above. All chromosome coordinates are referring to the UCSC Genome Browser Assembly May 2004 (hg17/ NCBI Build 35; available at: http://genome.ucsc.edu/cgi-bin/hgGateway?hgsid=99195739&clade=vertebrate&org=Human&db=hg17). Cytoscape {Shannon, 2003 #201} was used for the elucidation of potential interactions between genes within the intervals of interest.

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Comparative genomic hybridization suggests a role for NRXN1 and APBA2 in schizophrenia

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