Production of a mouse line with a conditional Crim1 mutant allele

Crim1 is a developmentally expressed, transmembrane protein essential for normal embryonic development. We generated mice engineered to contain a Crim1 conditional null allele by flanking exons three and four of Crim1 with unidirectional LoxP sites. After crossing Crim1 +/FLOX mice with a CMV‐Cre line, a Crim1 +/Δflox colony was established after germline transmission of the deleted allele. We then analyzed genomic DNA, mRNA transcripts, and protein expression from Crim1 Δflox/Δflox null mice to confirm the nature of the genomic lesion. Crim1 Δflox/Δflox mice displayed phenotypes similar to those previously described for a Crim1 gene‐trap mutant, Crim1 KST264/KST264 , including perinatal lethality, digit syndactyly, eye, and kidney abnormalities, with varying penetrance and severity. The production of a conditional mutant allele represents a valuable resource for the study of the tissue‐specific roles for Crim1 , and for understanding the pleimorphic phenotypes associated with Crim1 mutation. genesis 50:711–716, 2012. © 2012 Wiley Periodicals, Inc.