The purpose of this paper was to investigate the mediatory effects of polymorphisms in the cry1 gene on depressive and manic relapses in those with bipolar disorder (based on DSM-IV criteria). The study of 654 American bipolar patients has found a SNP in cry1 (rs10861688) that is associated with the number of depressive events in bipolar disorder.
rs10861688 in cry1
NCBI Variation Viewer rs10861688
Given the many studies of circadian genes and mood disorders, the authors investigated sirt1 SNPs as mediators of the pathogenesis of Hamilton Rating Scale for Depression diagnosed major depressive disorder (MDD). The study of 450 Japanese people with MDD and 766 healthy controls working in hospitals found that a sirt1 gene SNP (rs10997875) is associated with MDD. The authors also tested for a gene-anti-depressant interaction, but the association was not significant.
rs10997875 in sirt1
NCBI Variation Viewer rs10997875
To explain the altered sleep patterns in people with schizophrenia, a Chinese study of 148 schizophrenics (as diagnosed via Chinese classification and diagnostic criteria of mental disorders-2nd Edition-Revised) and 199 controls assessed the associations between the clock SNP rs1801260 and schizophrenia.
The study found that those with schizophrenia (as diagnosed by the Chinese classification and diagnostic criteria of mental disorders-2nd Edition-Revised) were more likely to have this SNP.
rs1801260 in clock
NCBI Variation Viewer rs1801260
The purpose of this study was to assess the relationship between SNPs in the clock gene and adult attention-deficit hyperactivity disorder (ADHD). The study included 143 German men aged 31.3 ± 11.7 (mean ± standard deviation), who were genotyped for SNPs via blood samples and ADHD status was assessed by self report followed by the Wender–Reimherr diagnostic interview.
A SNP in the clock gene (rs1801260) was found to be associated with ADHD by non-parametric analysis of covariance, adjusting for age, presence of personality disorders and multiple comparisons. Compared to those homozygous for the C/C alleles, those homozygous for the T/T allele had higher scores on measures of ADHD.
rs1801260 in clock
NCBI Variation Viewer rs1801260
A case-control study was performed to determine the role of circadian genes in male infertility. The study consisted of 517 cases and 444 controls, all of which were of Slavic origin and recruited from three outpatient fertility centres. A chi-square test found three SNPs (rs11932595, rs6811520, and rs6850524) on the clock gene that are associated with male clinician-diagnosed infertility. A haplotype analysis was then performed and confirmed the association.
The SNPs in the clock gene
NCBI Variation Viewer rs11932595-rs6811520-rs6850524
This study investigated the circadian genetic influence on sleep disorders and chronotypes. Visitors to the London Science Museum were recruited and completed the Horne-Östberg diurnal preference questionnaire and provided buccal DNA samples. In addition, a second patient population of individuals diagnosed with delayed sleep phase disorder (DSPD) were investigated. The authors found that those with the rs2797687 SNP on per3 were more likely to have DSPD compared to individuals with an evening chronotype. The TA2G haplotype was also associated with DSPD, as compared to evening chronotypes.
rs2797687 SNP in per3
NCBI Variation Viewer rs2797687
This Finnish study aimed to investigate the relationship between circadian clock genes and fertility. 511 subjects, aged 30 or older, were recruited from a national cohort. They underwent a diagnostic mental health interview, completed a modified Seasonal Pattern Assessment Questionnaire and genotyping was performed from patient blood samples.
Many nominally significant associations were found before correcting for multiple testing. The one association still significant after false discovery rate adjustment was that women homozygous for the rs2278749 SNP in the bmal1 gene experience a higher number of miscarriages than those with a wild type allele.
rs2278749 in bmal1
NCBI Variation Viewer rs2278749
A study in 820 North Americans and 728 people living in the Mediterranean area was carried out to evaluate the role of genetics in insulin resistance. The subjects were recruited from weight loss clinics (Mediterranean) or from the Blood Institute Family Heart Study field centers (American), and measures of blood and diet via (Diet History Questionnaire or 24 hour recall) were recorded.
The author found that greater carbohydrate intake is associated with increased insulin resistance in Mediterraneans with the CC allele of cry1 SNP rs2287161 versus those with non-CC alleles. This effect was nearly significant in the North American population as well. Additionally, they found that the effect of carbohydrate intake on predicted insulin resistance was dependant on genotype.
rs2287161 in cry1
NCBI Variation Viewer rs2287161
Parkinson’s disease patients tend to develop depression, and the authors of this paper assessed the role of circadian genetics in its pathogenesis. A genetic association study was performed in 408 Chinese patients with Parkinson’s Disease, and after adjusting for demographics, disease severity and treatment dose, the study found that the tef SNP rs738499 is associated with symptoms of depression (via the Hamilton Rating Scale for Depression) in people with Parkinson’s Disease.
rs738499 in tef
NCBI Variation Viewer rs738499
The purpose of this study of 90 adolescents was to determine the relationship between SNPs in circadian genes and reward mediating brain circuitry. The authors found that carriers of the G allele for the rs2304672 SNP in per2 tended to have less brain activity in the medial prefrontal cortex, an area of the brain associated with self-regulation, as measured by functional magnetic resonance imaging (fMRI).
rs2304672 in per2
NCBI Variation Viewer rs2304672