Recently, PDE4A5 has been shown to bind with disrupted in schizophrenia 1 (DISC1), which has been identified as a risk factor for schizophrenia, bipolar disorder, and major depression.
In a large Scottish pedigree, disruption of the gene coding for DISC1 clearly segregates with major depression, schizophrenia and related mental conditions.
In total, 14 single nucleotide polymorphisms (SNPs) in coding regions of 10 serotonergic genes (HTR1A, HTR1B, HTR1D, HTR2A, HTR3A, HTR3C, HTR3D, HTR3E, HTR5A and TPH2) were genotyped in 308 Chinese Han patients with major depressive disorder.
Although the majority of first-line antidepressants increase brain serotonin and rare polymorphisms in tryptophan hydroxlase-2 (Tph2), the rate-limiting enzyme in the brain serotonin synthesis pathway, have been identified in cohorts of subjects with major depressive disorder, the circuit level alterations that results from serotonergic hypofunction remain poorly understood.
In a large Scottish pedigree, a balanced translocation t(1;11) (q42.1;q14.3) disrupting the DISC1 and DISC2 genes segregates with major mental illness, including schizophrenia and unipolar depression.
A balanced chromosomal translocation disrupting DISC1 (Disrupted in Schizophrenia 1) gene has been linked to psychiatric diseases, such as major depression, bipolar disorder and schizophrenia.
Our findings provide evidence for an involvement of genetic variants of the TPH2 gene in the pathogenesis of MD and might be a hint on the repeatedly discussed duality of the serotonergic system.
Furthermore, an increased frequency of G allele of TPH2 SNP may be associated with elevated suicidal behavior itself rather than with the diagnosis of major depression and may increase risk of suicidality, independent of diagnosis.
This SNP and additional SNPs were discovered through a systematic characterization of the genetic architecture of the TPH2 gene for further genetic and functional investigations of its relationship to major depression and other psychopathology.
However, subsequent studies have shown association of DISC1 variants with a range of different neurocognitive phenotypes and psychiatric disorders, including bipolar disorder (BPD), and major depression.
TPH2rs4290270 was genotyped in 165 suicide attempters and 188 suicide non-attempters diagnosed with major depressive disorder, bipolar disorder and schizophrenia.
The Disrupted in Schizophrenia 1 (DISC1) gene has been associated with the risk of schizophrenia, schizoaffective disorder, bipolar disorder, major depression, autism, and Asperger syndrome in different populations.