Though rs1006737 in the CACNA1C gene showed significant association with MDD in a British large-scale candidate association study, most of the replication analyses with relatively small sample size reported negative association.
We found that rs1006737 was associated with both schizophrenia (P(allele) = 0.0014, P(genotype) = 0.006, odds ratio (OR) = 1.384, 95% CI 1.134-1.690) and major depressive disorder (P(allele) = 0.0007, P(genotype) = 0.003, OR = 1.425, 95% CI 1.160-1.752).
The current data provide further evidence for an impact of rs1006737 on the left IFG and demonstrate that genetic variation in CACNA1C modulates neural responses in patients with MDD.
The study population comprised 188 healthy first-degree relatives of patients with bipolar disorder (n=59), major depression (n=73), and schizophrenia (n=56) and 110 comparison subjects from our discovery study who were genotyped for rs1006737 and underwent functional magnetic resonance imaging while performing an episodic memory task and psychological testing.
Recent genome-wide association studies have pointed to single-nucleotide polymorphisms (SNPs) in genes encoding the neuronal calcium channel CaV1.2 (CACNA1C; rs1006737) and the presynaptic active zone protein Piccolo (PCLO; rs2522833) as risk factors for affective disorders, particularly major depression.
Suggestive but notable results were (a) gene-based tests suggesting roles for adenylate cyclase 3 (ADCY3, 2p23.3) and galanin (GAL, 11q13.3); published functional evidence relates both of these to MDD and serotonergic signaling; (b) support for the bipolar disorder risk variant SNP rs1006737 in CACNA1C (P=0.020, odds ratio=1.10); and (c) lack of support for rs2251219, a SNP identified in a meta-analysis of affective disorder studies (P=0.51).
Recent genetic studies found the A allele of the variant rs1006737 in the alpha 1C subunit of the L-type voltage-gated calcium channel (CACNA1C) gene to be over-represented in patients with psychosis, including schizophrenia, bipolar disorder and major depressive disorder.
The rs10994336 ANK3 and rs1006737 CACNA1C genetic variants have recently been identified as the most consistent, genome-wide significant risk factors for bipolar disorder, while the CACNA1C variant has also been associated with schizophrenia and major depression.
Recent genetic studies found the A allele of the variant rs1006737 in the alpha 1C subunit of the L-type voltage-gated calcium channel (CACNA1C) gene to be overrepresented in patients suffering from bipolar disorder, schizophrenia or major depression.
The single nucleotide polymorphisms FKBP5:rs1360780, BDNF:rs6265 (Val66Met), P2RX7:2230912 (Gln460Arg) and CACNA1C:rs1006737 were genotyped in DNA from 457 depression cases (major depression, dysthymia, and mixed anxiety depression) and 2286 healthy controls with no symptom of psychopathology.
Bivariate genome-wide association analyses of the broad depression phenotype combined with major depressive disorder, bipolar disorder or schizophrenia reveal eight novel genetic loci for depression.
Bivariate genome-wide association analyses of the broad depression phenotype combined with major depressive disorder, bipolar disorder or schizophrenia reveal eight novel genetic loci for depression.
We additionally analyzed other 25 SNPs, genotyped in only one replication study, across the CACNA1C locus, and found that two SNPs, rs4765905 (P = 0.041, OR = 1.05, 95%CI 1.00-1.09) and rs4765937 (P = 0.025, OR = 1.05, 95%CI 1.01-1.09) showed nominal association with MDD, while rs2239073 (P = 0.002, OR = 1.07, 95%CI 1.02-1.11) exhibited significant association with MDD, which survived from multiple corrections.