WAGR (Wilms tumor, aniridia, genito-urinary abnormalities, mental retardation) syndrome in humans is associated with deletions of the 11p13 region. The brain-derived neurotrophic factor (BDNF) gene maps to this region, and its deletion seems to contribute to the severity of the patients' mental retardation. Yeast artificial chromosomes (YACs) carrying the BDNF gene have been isolated and characterized. Localization of two known exons of this gene leads to a minimal estimation of its size of about 40 kb. Chimerism of the BDNF YACs has been investigated by fluorescence in situ hybridization and chromosome assignment on somatic cell hybrids. Using the BDNF gene, YAC end sequence tagged sites (STS), and Généthon microsatellite markers, we constructed a 1.7-Mb contig and refined the cytogenetic map at 11p13. The resulting integrated physical, genetic, and cytogenetic map constitutes a resource for the characterization of genes that may be involved in the WAGR syndrome.