The transgene comprises a yeast artificial chromosome (YAC) from the CEPH Whole Genome MegaYAC Library carrying a 430-kb fragment of DNA from human Chromosome 21 that includes the potassium inwardly-rectifying channel, subfamily J, member 6 gene, KCNJ6 (also called GIRK2, KIR3.2 or HUM21ES123), which is expressed in the brain both in humans and in mice bearing the YAC as a transgene. Line 67 was shown by length-adjusted quantitative Southern blot analysis to bear a single copy of the 430-kb YAC. (J:128897)