Vector PG00123_Y_1_H12 from Helmholtz Zentrum Munchen was modified and used to generate mice. A G to A transition at position 905 (c.G905A) resulting in an arginine to histidine substitution at amino acid 302 (p.R302H) was introduced in exon 4. In addition, an FRT-flanked neomycin selection cassette and loxP site were inserted upstream of exon 3 and a second loxP site was inserted downstream of mutated exon 4. (J:282272)