SLC6A4 and major depressive disorder: The tolerability of Sertraline, its titration and the maximum Sertraline dose utilised were shown to be associated with HTR2A, Solute carrier family 6 member 4 (SLC6A4) and Glutamate ionotropic receptor kainite type subunit 4 (GRIK4) polymorphisms in youth with anxiety and/or major depressive disorder [68].