A new human brain cDNA molecule was mapped by in situ hybridization to the 11q21-q23.1 region of the human genome, probably to the 11q22 band. An EcoRI restriction site and a (GT)n repeat element within the gene were shown to be polymorphic. Both polymorphisms were readily studied by the polymerase chain reaction. A two-allele polymorphism was described for the EcoRI restriction site, whereas four different alleles were detected for the second genetic marker. The observed heterozygosities were 37% and 42% for the former and the latter polymorphism, respectively. The combined heterozygosity index was estimated to be 0.56. These new genetic markers will be useful for linkage analysis of neurogenetic diseases that have been mapped to this chromosomal region.