SMPDL3B and attention deficit-hyperactivity disorder: Using the single-locus LMEM, we identified seven markers significantly associated with persistent ADHD (rs74073730 in GALC, rs4668077 in CERS6, rs35785620 in SMPD1, rs143078230 in SMPDL3B, rs139609178 in CERS2, rs200333847 in FADS3, and rs41273880 in ELOVL5) (Table 2a).