Sequences encoding the BDNF protein replaced the entire coding region of the Ntf3 gene. A loxP flanked neomycin cassette was inserted adjacent to the coding region of the gene, but was removed via cre-mediated recombination in the final allele. Northern blot analysis and in situ hybridization analysis confirmed expression of a Bdnf transcript from this allele that mimicked the expression pattern of the endogenous Ntf3.