rs1801260, a SNP in the CLOCK gene known as 3111 T/C, has been reported to influence sleep and activity patterns in patients affected by bipolar depression. [PMID 17221848]
From this article's abstract:
"Compared to T/T homozygotes, carriers of the C allele had a similar degree of severity of depression, but showed higher activity levels in the evening, a delayed sleep onset (mean 79 min later), and a reduced amount of sleep during the night (mean 75 min less)."
[PMID 20364331] Allele frequencies of T3111C SNP of hClock were significantly different between schizophrenics and controls (chi(2) = 19.738, P < 0.05). Schizophrenics had a significantly higher frequency of the C allele compared with controls (OR = 2.613, 95% CI = 1.693-4.034). (Han Chinese population.)
[PMID 17948273] There was a strong, significant association (P < 0.001) between both self-rating and interview-based adult ADHD assessments and the rs1801260 polymorphism with at least one T-mutation being the risk allele.
[PMID 20065968] rs1801260 variations associated with weight loss while on Mediterranian diet. Carriers of the G allele displayed greater difficulty in losing weight than non-carriers.
[PMID 17428266] CLOCK 3111 T/C SNP was associated with activity levels in the second part of the day, neuropsychological performance and BOLD fMRI correlates (interaction of genotype and moral valence of the stimuli).
[PMID 20704703] Association study between a polymorphism at the 3'-untranslated region of CLOCK gene and attention deficit hyperactivity disorder
[PMID 21773969] Functional polymorphisms of circadian positive feedback regulation genes and clinical outcome of Chinese patients with resected colorectal cancer
[PMID 22517501] Rotating night shift work and polymorphism of genes important for the regulation of circadian rhythm
[PMID 18071340] Association between polymorphisms in the Clock gene, obesity and the metabolic syndrome in man.
[PMID 18228528] Clock genes may influence bipolar disorder susceptibility and dysfunctional circadian rhythm.
[PMID 18663240] Genetic differences in human circadian clock genes among worldwide populations.
[PMID 18957941] Genome-wide association scan for five major dimensions of personality.
[PMID 19166596] Circadian polymorphisms associated with affective disorders.
[PMID 20180986] CLOCK is suggested to associate with comorbid alcohol use and depressive disorders.
[PMID 20368993] ARNTL (BMAL1) and NPAS2 gene variants contribute to fertility and seasonality.
[PMID 20396431] Genotyping sleep disorders patients.
[PMID 20600471] Association between CLOCK 3111T/C and preferred circadian phase in Korean patients with bipolar disorder.
[PMID 22310473] SIRT1 and CLOCK 3111T>C combined genotype is associated with evening preference and weight loss resistance in a behavioral therapy treatment for obesity.
[PMID 23131019] Physical Activity and Sex Modulate Obesity Risk Linked to 3111T/C Gene Variant of the CLOCK Gene in an Elderly Population: The SUN Project