We conclude that dyslexia may be caused by partial haplo-insufficiency for ROBO1. In addition, we searched for novel exons and splice variants of ROBO1 that may help in understanding the apparent phenotypic discrepancy between heterozygous Dutt1and Robo1 knockout mice that develop lung cancers and lymphomas and humans whose developmental phenotypic consequence appears to be dyslexia. Here, ROBO1 is linked to lung carcinoma.