Although the L variant has been associated with higher levels of SERT gene products and higher reuptake activity, S allele carriers were reported to be more susceptible to depression.28,29 Contrary to the recent report by Saul, et al. who found an association between depression severity in patients with MS with one or two copies of the 5-HTTLPR S allele,30 the frequency of S allele carriers in the present study did not differ significantly between patients with MS who reported feeling depressed and those with normal psychological status (53% vs. 51%). This evidence concerns the gene SLC6A4 and depressive disorder.