Bay Genomics gene trap vector pGt1Lxf was randomly inserted 11kb downstream of exon 3 in intron 3 which is 75 kb in size. RNA for the wild-type allele was detected in the brain by RT-PCR along with a larger band in mice carrying the gene trap allele and lacking the wild-type allele (J:111316). An independent report indicated that this allele is hypomorphic and that residual low-level expression of a properly spliced transcript is found in homozygous mice (J:114758). (J:111316)