SLC6A15 and atopic march: A second novel variant associated with the atopic march, rs993226 (OR 1.58; P=5.3 × 10−9; Table 1), is located on chromosome 12q21.3, 1.36 Mb distal of transmembrane and tetratricopeptide repeat containing 2 (TMTC2) and 370 kb proximal of solute carrier family 6 (neurotransmitter transporter), member 15 (SLC6A15; Supplementary Fig. 4).