AbstractNeurodevelopmental disorders, such as autism spectrum disorders and schizophrenia, are complex disorders with a high degree of heritability. Genetic studies have identified several candidate genes associated with these disorders, including contactin-associated protein-like 2 (CNTNAP2). Traditionally, in animal models or in vitro, CNTNAP2 has been studied by genetic deletion or transcriptional knockdown, which reduces the expression of the entire gene; however, it remains unclear whether the mutations identified in clinical settings are sufficient to alter CNTNAP2 expression in human neurons. Here, using human induced pluripotent stem cells (hiPSCs) derived from two individuals with a large (289 kb) heterozygous deletion in CNTNAP2 (affecting exons 14–15) and discordant clinical outcomes, we have characterized CNTNAP2 expression patterns in hiPSC neural progenitor cells, two independent populations of hiPSC-derived neurons and hiPSC-derived oligodendrocyte precursor cells. First, we observed exon-specific changes in CNTNAP2 expression in both carriers; although the expression of exons 14–15 is significantly decreased, the expression of other exons is upregulated. Second, we observed significant differences in patterns of allele-specific expression in CNTNAP2 carriers that were consistent with the clinical outcome. Third, we observed a robust neural migration phenotype that correlated with diagnosis and exon- and allele-specific CNTNAP2 expression patterns, but not with genotype. In all, our data highlight the importance of considering the nature, location, and regulation of mutated alleles when attempting to connect genome wide association studies to gene function.