Study Report

Reference	Souery, D.,2001 PMID: 11274651
Citation	Souery, D., S. Van Gestel, et al. (2001). "Tryptophan hydroxylase polymorphism and suicidality in unipolar and bipolar affective disorders: a multicenter association study." Biol Psychiatry 49(5): 405-409.
Disease Type	Bipolar Disorder & Major Depressive Disorder
Study Design	case-control
Study Type	Candidate-gene association study
Sample Size	927 patients (527 BPAD and 400 UPAD) and 927 matched healthy control subjects
SNP/Region/Marker Size	1 variant
Predominant Ethnicity	Caucasian
Population	European

Sample Diagnosis	DSM
Sample Status	A total of 927 patients (527 BPAD and 400 UPAD) and their matched healthy control subjects have been included with DNA available. Each patient is matched to a control subject of the same ethnogeographic origin, the same gender, and a maximal age difference of 5 years. All these subjects have been diagnosed using the Schedule for Affective Disorders and Schizophrenia-Lifetime Versions (SADS-LA) or the Schedules for Clinical Assessment of Neuropsychiatry (SCAN). All the patients met the diagnosis of BPAD or UPAD according to Research Diagnostic Criteria, DSM-III-R, and DSM-IV classification systems. One of the two diagnostic interviews was used for all patients and control subjects recruited for the project. The decision to adopt two instruments arose out of different research experience within individual research teams having their own preferences and expertise with the two interviews. Comparability between SADS and SCAN instruments is inferred from data published by the European Science Foundation (Farmer et al 1993) showing good concordance between the two instruments.
Technique	PCR and RFLP
Statistical Method	chi-square tests
Result Summary	RESULTS: No difference of genotype distribution or allele distribution was found in BPAD or UPAD. No statistically significant difference was observed for allele frequency and genotypes counts. In a genotype per genotype analysis in UPAD patients with a personal history of suicide attempt, the frequency of the C-C genotype (homozygosity for the short allele) was lower in UPAD patients (24%) than in control subjects (43%) (chi(2) = 4.67, p =.03). There was no difference in allele or genotype frequency between patients presenting violent suicidal behavior (n = 48) and their matched control subjects. CONCLUSIONS: We failed to detect an association between the A218C polymorphism of the TPH gene and BPAD and UPAD in a large European sample. Homozygosity for the short allele is significantly less frequent in a subgroup of UPAD patients with a history of suicide attempt than in control subjects.