title: Screening the human protocadherin 8 (PCDH8) gene in schizophrenia.
abstract: Abnormalities in synaptic connectivity and plasticity have been implicated in the pathophysiology of schizophrenia. Molecules involved in the development and maintenance of neural circuitry include the recently cloned protocadherins. Human protocadherin 8 (PCDH8) is homologous to 'arcadlin', a molecule shown to play a role in hippocampal synaptic function in the rat. The gene encoding PCDH8 maps to a region on chromosome 13 where linkage to schizophrenia has been reported. In this study, the entire expressed sequence of the PCDH8 gene and over 800 bp of the 5' flanking region were screened for polymorphisms in 30 DSM-IV schizophrenia individuals using Denaturing High Performance Liquid Chromatography (DHPLC). A total of nine single nucleotide polymorphisms were identified, including three in the first exon that are predicted to change the amino acid sequence. One polymorphism, causing the Trp7Arg change in the putative signal peptide, showed a trend towards excess of the arginine encoding allele in a case-control sample consisting of 520 DSM-IV schizophrenia patients and 535 matched controls from the UK (chi2=3.72, P [1 df]= 0.054). However, this polymorphism did not show preferential transmission to schizophrenic individuals in a separate sample of 203 proband-parent trios from Bulgaria. A second, rare single nucleotide variation, predicting the non-conservative amino acid change Glu39Ala, was found in one schizophrenic individual and their affected sibling but not in a further 352 affected individuals, nor 357 controls. These results suggest that any contribution of PCDH8 polymorphisms to schizophrenia susceptibility is likely to be weak, although the existence of rare variations of stronger effect cannot be excluded.
authors.affiliation: Department of Psychological Medicine, University of Wales College of Medicine, Heath Park, Cardiff CF14 4XN, UK. braynj@cardiff.ac.uk
authors.forename: N J
authors.initials: NJ
authors.lastname: Bray
authors.forename: G
authors.initials: G
authors.lastname: Kirov
authors.forename: R J
authors.initials: RJ
authors.lastname: Owen
authors.forename: N J
authors.initials: NJ
authors.lastname: Jacobsen
authors.forename: L
authors.initials: L
authors.lastname: Georgieva
authors.forename: H J
authors.initials: HJ
authors.lastname: Williams
authors.forename: N
authors.initials: N
authors.lastname: Norton
authors.forename: G
authors.initials: G
authors.lastname: Spurlock
authors.forename: S
authors.initials: S
authors.lastname: Jones
authors.forename: S
authors.initials: S
authors.lastname: Zammit
authors.forename: M C
authors.initials: MC
authors.lastname: O'Donovan
authors.forename: M J
authors.initials: MJ
authors.lastname: Owen
mesh_terms: D000328:Adult; D000595:Amino Acid Sequence / Q000235:genetics; D001921:Brain / Q000503:physiopathology; D015820:Cadherins / Q000235:genetics*; D016022:Case-Control Studies; D002898:Chromosomes, Human, Pair 8; D004252:DNA Mutational Analysis; D005091:Exons; D020022:Genetic Predisposition to Disease / Q000235:genetics; D005820:Genetic Testing; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D009710:Nucleotide Mapping; D010641:Phenotype; D011110:Polymorphism, Genetic / Q000235:genetics; D012150:Polymorphism, Restriction Fragment Length; D000091363:Protocadherins; D012559:Schizophrenia / Q000175:diagnosis / Q000235:genetics* / Q000503:physiopathology; D017422:Sequence Analysis, DNA
chemical_list: D015820:Cadherins; C115816:PCDH8 protein, human; D000091363:Protocadherins