Linkage disequilibrium (LD) analysis of schizophrenia (SC) in the Costa Rican population: Preliminary findings on chromosome 18

T. G. Balderas, A. P. Montera, E. Benavides, S. Rodriguez, L. Almasy, H. Raventos, M. A. Escamilla

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    2 Scopus citations


    In prior studies of Bipolar I Disorder (BPI) with patients from Costa Rica, a possible locus for BPI at 18pter has been reported in both a pedigree based analysis and a population based analysis (McInnes et al., 1996, Escamilla et al., 1999). We tested the same region on chromosome 18 with a sample of 79 Costa Rican persons with a best estimate diagnosis of SC (DSM-IV). Initially we tested six markers, starting at D18S1140 and ending at D18S452, spanning a total of 24.3 cM. Alleles from a total of 158 chromosomes from probands and 189 control chromosomes, were compared using the CLUMP test of Sham and Curtis and the Terwilliger LD test. We found evidence of LD (P =.02) and association (P =.02) at D18S63. We followed this finding up by genotyping three additional markers lying close to D18S63. One of these additional markers, D18S54 also showed evidence of association (P =.05). The marker which shows the strongest evidence of association to SC chromosomes in our sample (D18S63) is 6.3 cM from the markers that have shown association with BPI chromosomes in this same population (D18S59 and D18S476). Two possible explanations are 1) that there are independent predisposition genes for BPI and for SC located in this region, or 2) that BPI and SC are allelic variants for a predisposition gene to psychosis located in this region. We will eventually analyze these results using haplotype analysis (including Ancestral Haplotype Reconstruction) in order to better evaluate the region in 18pter associated with SC patients from Costa Rica.

    Original languageEnglish (US)
    Pages (from-to)599-600
    Number of pages2
    JournalAmerican Journal of Medical Genetics - Neuropsychiatric Genetics
    Issue number7
    StatePublished - Oct 8 2001

    ASJC Scopus subject areas

    • Genetics(clinical)
    • Psychiatry and Mental health
    • Cellular and Molecular Neuroscience


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