This allele is a derivative of Fgfr2tm1Dsn in which exon IIIb was excised in the germline as follows: Cre recombinase was transiently expressed in fertilized C57BL/6 x Fgfr2tm1Dsn/tm1Dsn eggs by injection of an expression vector. Resulting progeny were screened for animals with a deletion of exon IIIb. Abnormally spliced transcripts are produced from this allele that splice exon IIIa to the transmembrane domain and the resulting frameshift is predicted to result in a termination codon in the transmembrane domain of the encoded protein. However, a normal IIIa to IIIc and TM transcript is made and is prediced to result in a normal isoform of the protein.