Gene SLC6A4

Something cool that I learned recently...

The serotonin transporter gene SLC6A4 is polymorphic with three distict alleles (consisting of a 44bp insertion or deletion): s/L, s/s, L/L. People with an s allele (genotype s/s or s/L) tend to have lower functioning of the serotonin transporter, which is indirectly associated with depression. Essentially, having an s allele doesn't cause depression, but combined with specific environmental factors (nurture) it is significantly more likely to result in a depressive episode. Unfortunatley, this allele is also associated with poorer outcomes of SSRI (selective serotonin re-uptake inhibitor) treatment; currently the most prevelant drug prescribed for depression.