A cross-sectional study of 856 Argentinian factory workers was performed to determine whether mutations in the serotonin-transporter-linked polymorphic region (5-HTTLPR) of the serotonin transporter gene (SLC6A4), combined with the presence of clock gene SNPs, had an effect on several markers of metabolic syndrome.
They found that the homozygous rs1554483G–rs4864548A clock haplotype and 5-HTTLPR mutations together were associated with higher systolic and diastolic blood pressure as well as increased plasma triglyceride concentrations in rotating shift workers. Conversely, in day workers with both mutations, these outcomes were decreased. A similar epistatic finding was found with the heterozygous rs1554483G–rs4864548A clock haplotype and diastolic blood pressure.
rs1554483G–rs4864548A in clock