title: Pilot study for family-based association analysis of schizophrenia in a Korean population: Analysis for candidate genes positionally on chromosome 18q21.
abstract: BACKGROUND
  Schizophrenia is the most devastating mental illness that causes severe deterioration in social and occupational functioning. This is a pilot study for family-based association analysis of schizophrenia in a Korean population to search candidate genes functionally relevant and positionally on chromosome 18.
  
  
  METHODS
  We have recruited 27 probands (with psychosis) with their parents and siblings whenever possible. We analyzed 20 SNPs (Single Nucleotide Polymorphism) of seven neuronal genes in chromosome 18 for DNA samples that was checked for the data quality and genotype error. For testing of association, we performed family-based association tests analyses with each individual SNP, using the phenotype of psychosis. And then, we performed family-based association tests haplotype analyses with each individual SNP, using the phenotype of psychosis. Finally, we performed linkage disequilibrium analyses for the phenotype of schizophrenia.
  
  
  RESULTS
  We found one significant SNPs of one neuronal gene in chromosome 18 (P value < 0.05) for the qualitative phenotype of psychosis (rs1893490:MAPK4). We also found significant haplotypes of four SNPs in mitogen-activated protein kinase 4 (MAPK4) gene of chromosome 18 (P value < 0.1) for the phenotype of psychosis (rs1893490-rs3892158-rs3752088-rs3794899). Two SNPS within the MAPK4 gene (rs3794899, rs3794901), plus SNPs within the malic enzyme 2 (rs685533, rs12277), and SMAD4 genes (rs8096092, rs2298617) were in strong linkage disequilibrium with each other (D' > 0.60).
  
  
  CONCLUSIONS
  The present findings provide convergent evidence (fine mapping of a chromosomal locus 18q21 associated with schizophrenia) suggesting that a specific MAPK4 could be a candidate gene for causing a spectrum of schizophrenia phenotype.
authors.affiliation: Department of Pediatrics, Pusan National University Hospital, Busan, South Korea.|Medical Research Institute, Pusan National University Hospital, Busan, Republic of Korea.
authors.forename: Min Jung
authors.initials: MJ
authors.lastname: Cho
authors.affiliation: Department of Psychiatry, Pusan National University Hospital, Busan, South Korea.|Department of Psychiatry, Pusan National University College of Medicine, Kyungnam, Republic of Korea.|Medical Research Institute, Pusan National University Hospital, Busan, Republic of Korea.
authors.forename: Byung Dae
authors.initials: BD
authors.lastname: Lee
authors.affiliation: Department of Statistics, Pusan National University, Busan, Republic of Korea.
authors.forename: Choongrak
authors.initials: C
authors.lastname: Kim
mesh_terms: D002887:Chromosomes, Human, Pair 18 / Q000235:genetics*; D006239:Haplotypes; D006801:Humans; D015810:Linkage Disequilibrium / Q000235:genetics; D008291:Malate Dehydrogenase / Q000235:genetics; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics; D010865:Pilot Projects; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D056910:Republic of Korea / Q000208:ethnology; D012559:Schizophrenia / Q000208:ethnology / Q000235:genetics*
chemical_list: D008291:Malate Dehydrogenase; C495394:malic enzyme 2; human; D020928:Mitogen-Activated Protein Kinases
keywords: Korean; association; family; genetic; schizophrenia