Study Report

Reference	Ikeda, M., 2006 PMID: 16082508
Citation	Ikeda, M., N. Iwata, et al. (2006). "No association of serotonin transporter gene (SLC6A4) with schizophrenia and bipolar disorder in Japanese patients: association analysis based on linkage disequilibrium." J Neural Transm 113(7): 899-905.
Disease Type	Bipolar Disorder & Schizophrenia
Study Design	case-control
Study Type	Mutation study and candidate-gene association study
Sample Size	37 and 27 patients with SCZ and bipolar I disorder for the mutation research; 96 controls for LD mapping; 287 patients with SCZ, 109 patients with BP and 288 controls for the association analysis.
SNP/Region/Marker Size	13 variants
Predominant Ethnicity	Mongloid
Population	Japanese
Gender	148 male and 139 female patients with SCZ, 51 male and 58 female patients with BP and 150 male and 138 female controls
Age Group	adults : mean age=42.3 (SD=14.7) years of SCZ patients, mean age=48.3 (SD=13.2) years of BP patients, mean age=33.6 (SD=12.9) years of controls

Sample Diagnosis	DSM-IV
Sample Status	287 patients with SCZ and 109 patients with BP (61 patients with Bipolar I disorder and 48 patients with bipolar II disorder) were diagnosed according to DSM-IV criteria with the consensus of at least two experienced psychiatrists on the basis of unstructured interviews and review of the medical records.
Technique	SNP identification, LD mapping and SNP genotyping using TaqMan, PCR, or direct sequencing
Statistical Method	Marker-trait association was evaluated allele/genotype-wise with conventional chi square test or Fisher's exact test and haplotype-wise with the program COCAPHASE 2.403. The COCAPHASE program performs log-likelihood ratio tests under a log-linear model for global P-value. To estimate haplotype frequencies of 'tagging' markers, the expectation-maximization (EM) algorithm was used. Power calculation was performed using a statistical program prepared by Ohashi et al. (2001). The significance level for all statistical tests was 0.05.
Result Summary	In this mutation search, a nonsynonymous SNP, Asn605Lys, was detected. No associations of 'tagging' markers and independent markers with such conditions were found. These results indicate that SLC6A4 might not play a major role in SCZ and BP in Japanese patients, a finding that agrees with both the common diseasecommon variant hypothesis and common disease-rare variant hypothesis.