GRPR and autism: Although a subsequent study investigating two polymorphic sites in the second exon of the GRPR gene in patients did not support the GRPR as a candidate locus for autism (Marui et al., 2004), more recently a possible role of C6S and L181F mutations of the GRPR gene in GRPR function and ASD was found in two patients (Seidita et al., 2008).