Smn1^{tm5(Smn1/SMN2)Mrph}

The allele encodes two coding sequences: the first is a hybrid gene in which a 2.2 kb segment of mouse genome containing exons 7 and 8 of the mouse Smn1 gene was replaced with a 1.3 kb fragment of human genomic DNA containing exons 7 and 8 of the human SMN2 gene and the second is a full 42 kb copy of the human SMN2 gene. A selection cassette located downstream from the human SMN2 polyadenylation signal was removed by FLPe expression in ES cells leaving a FRT site at the downstream junction between human and mouse DNA. Because exon 7 is derived from human SMN2, it is skipped in approximately 90% of the processed mRNA derived from both genes. 2 independent clones for this allele were generated and clone A2 was used to generated mice. (J:135425)