Fgf17 Conditional Knockout mouse models

Fgf17, mouse ortholog of human FGF17, is a member of the FGF8 subfamily and encodes a secreted ligand with strong preference for the c-splice receptors FGFR1c, FGFR2c, FGFR3c, and FGFR4, acting alongside FGF8 at the midbrain-hindbrain isthmic organizer and in the anterior neural ridge to pattern frontal cortex, cerebellar vermis, and rostral telencephalon. Nulls are viable but show hypoplasia of the cerebellar vermis, reduced dorsomedial frontal cortex, and altered social behavior, phenotypes that map cleanly onto region-specific FGF dosage. In humans, heterozygous variants have been reported in Kallmann syndrome and normosmic hypogonadotropic hypogonadism, consistent with GnRH neuron and olfactory placode requirements shared with FGF8 and FGFR1. Because viability permits constitutive deletion, the informative designs are hypomorphic allelic series and compound Fgf8 and Fgf17 alleles that titrate isthmic signal, since these two ligands substantially overlap. Reserve conditional floxed alleles with En1-Cre or Emx1-Cre for questions that separate organizer patterning from later cortical growth endpoints.

Tissue restricted knockout of Fgf17 keeps wild type function everywhere else. Breeding is often more robust, and the setup mirrors patient biology where mutations arise in a subset of cells.