In contrast, previous candidate gene studies in Caucasian children with ASD (Correia et al., 2009; Rafaniello et al., 2017) and adults with schizophrenia (Xing et al., 2006; Kuzman et al., 2008) have linked reduced RIS efflux with other ABC transporter subtype mutations (ABCG2_c.421C>A in ABCG2; c.3435C>T, c.1199G>A, c.1236C>T and c.2677G>T in ABCB1). Here, ABCG2 is linked to schizophrenia.