Exon 9 was replaced with a modified exon containing a C-to-T point mutation (c.952C>T) that results in the introduction of a stop codon in place of an arginine codon (p.R318*). Flp-mediated recombination removed and FRT-flanked neomycin resistance cassette inserted into intron 8. The absence of protein expression was confirmed. The mutation is the equivalent of the human UNIPROT:Q8NF50:p.R317* mutation found in some combined immunodeficiency patients. (J:237279)