Mice that are homozygous for the targeted mutation are viable, fertile, normal in size and do not display any gross physical or behavioral abnormalities. None of the major splice variants of Fmn1 are detected by Northern blot analysis. No gene product (protein) is detected by Western blot analysis of MEFs. Homozygotes display digital oligodactyly phenotype, with absent fibula. 50% of homozygotes (on the FVB background) exhibit unilateral renal aplasia. This mutant mouse strain may be useful in studies of limb development, digital oligodactyly, and kidney development. The Jackson Laboratory 2024, used with permission.