Study Report

Reference	Zhang X, 2013 PMID: 23680436
Citation	Zhang, X., C. Zhang, et al. (2013). "Association of genetic variation in CACNA1C with bipolar disorder in Han Chinese." J Affect Disord.
Disease Type	bipolar disorder & MDD
Study Design	case-control
Study Type	Candidate-gene association study
Sample Size	635 MDD patients, 286 BD patients and 730 controls
SNP/Region/Marker Size	3 SNPs
Predominant Ethnicity	Mongloid
Population	Chinese
Gender	241 male MDD patients, 116 male BD patients, 288 male controls
Age Group	adults : mean age=37.9 (SD=12.5) years of MDD patients, mean age=32.7 (SD=11.4) years of BD patients, mean age=34.5 (SD=6.8) years of controls

Sample Diagnosis	DSM-IV
Sample Status	The MDD patients used in this study were comprised of both inpatients and outpatients from our multicenter, longitudinal 'OPERATION' study, 'OPERATION-ECMA' study,and 'CARE-SSD/ MDD' study,conducted between January 2005 and October 2010. The patients who met DSM-IV criteria for BD type1 or type 2 were recruited from the Division of Mood Disorders at Shanghai Mental Health Center, Shanghai JiaoTong University School of Medicine between November 2006 and October 2010.
Technique	genotyping using the TaqMan SNP Genotyping Assay
Statistical Method	The differences in distribution of allele frequencies between cases and controls were calculated on SHEsis. Deviation from Hardy-Weinberg equilibrium, as well as pair-wise linkage disequilibrium(LD) for all pairs of SNPs and haplotype analysis were performed by using Haploview4.1. All calculations were performed using SPSS17.0. Power analysis was performed using Quanto 1.2.3. For multiple test correction, the Bonferroni p-value cut-off was set at 0.0125.
Result Summary	The genotype frequencies of SNP rs1051375 showed statistically significant differences between the BD and control groups (P=0.005). At the allele level, the difference of G allele frequency of rs1051375 between BD patients and control subjects was also significant (P=0.011; OR=1.30, 95% CI: 1.06-1.58). We found that GG genotype of rs1051375 carriers had a lower age at onset than those with the AG or AA genotype, and the mean+/-standard deviation ages at onset of GG, AG and AA carriers were 24.04+/-4.22, 25.76+/-4.75 and 25.78+/-4.33 years, respectively. Neither genotype nor allele frequencies of the three polymorphisms were found to be significantly different between the MDD patients and control subjects. LIMITATIONS: The relative small sample size in BD group should be considered a limitation of this study. Our initial findings support a potential association of CACNA1C as a genetic risk factor for BD susceptibility.