Rs6318

rs6318 (Cys23Ser / C23S or 68G>C / G68C) is a SNP within the serotonin 2C receptor HTR2C gene located on the X chromosome. Since it is located on the X chromosome, males will be hemizygous and either (C;-) or (G;-), whereas females will either homozygous (C;C) or (G;G) or heterozygous (C;G). In most of the studies cited below, heterozyous (C;G) females were roughly statistically equivalent to females carrying the common non-risk (G;G) genotype.

One relatively large (4,000 men and 2,000 women) study published in late 2013 of Caucasian catheterization patients has studied the association between rs6318 genotype and risk of having an "end" cardiac event, defined as either death or a heart attack, in the years following entry into the study (i.e. presumably following their catheterization). Patients were followed for up to 11 years, with a median follow-up time of 5.3 years. Different rs6318 genotypes had statistically significant differences in their odds of having end cardiac events as follows: 29% of (G;-) men; 35% of (C;-) men; ~26% of (G;G) or (C;G) women; and 36% of (C;C) women. This works out to hazard ratios from the fully adjusted model for male rs6318(C;-) compared to the more common (G;-) males of 1.23 (CI: 1.02-1.36, p=0.02), and 1.62 (CI:1.07-2.47, p=0.02) for female (C;C) genotypes compared to the more common (G;G) females. The authors postulate that rs6318 is associated with higher stress-related cortisol levels, and suggest (without any evidence so far) that rs6318(C;C) women and (C;-) men may benefit from either behavioural therapy or the use of a serotonin receptor antagonist such as agomelatine.

'significant excess of Ser allele carriers in patients compared to normal controls' (in 513 patients with recurrent MDD, 649 patients with bipolar affective disorder, and 901 normal controls)

Further evidence supporting the association between 5HTR2C gene and bipolar disorder

antipsychotics
in a small sample of 45 autistic patients taking risperidone for up to one year, assoc. w/ prolactin elevation and BMI / waist circumference with risperidone usage

rs6313(T) (102T) allele of HTR2A, the rs5443(T) (825T) allele of GNB3, the Rs6318(G) (23Cys) allele of HTR2C, and the rs1801253(C;C) (64Arg/Arg) genotype of ADRB3, were significantly associated with olanzapine-induced weight gain among 164 schizophrenic (per DSM-IV-TR) psychiatric inpatients

no association with anti-psychotic induced weight gain noted in 104 Caucasian psychiatric inpatients