The transgene comprises the 130-kb RPCI PAC clone 204D22, containing the human adenylate cyclase activating polypeptide 1 receptor 1 (ADCYAP1R1; also called PAC1) gene, modified by insertion of an internal ribosomal entry site (IRES) followed by the lacZ coding sequence (IRES-lacZ-p[A] cassette) into the 3' untranslated region (3' UTR) downstream of the human gene's polyadenylation signal. In this mouse line, the transgene has integrated into the X Chromosome; thus, it can be used for X Chromosome inactivation and hydrocephalus-related phenotype studies. (J:111714)