The etiological mechanisms of the genetic underpinnings of developmental language disorder (DLD) are unknown, in part due to the behavioral heterogeneity of the disorder's manifestations. In this study, we explored an association between the SETBP1 gene (18q21.1), revealed in a genome-wide association study of DLD in a geographically isolated population, and brain network-based endophenotypes of functional intracortical coherence between major language-related brain areas. We analyzed electroencephalogram (EEG) data from thirty-nine children (twenty-three with, sixteen without DLD) aged 7.17–15.83 years acquired during an auditory picture–word matching paradigm. Variation at a single nucleotide polymorphism in the intronic region of the SETBP1 gene, rs8085464, explained 19% of the variance in intracortical network cohesion (p =.00478). This suggests that the development of these brain networks might be partially associated with the variation in SETBP1.