PPARG and Insulin resistance: Here, we describe the identification of five heterozygous human PPARγ mutations (C114R, C131Y, C162W, R357X, [A935ΔC]fs.312[stop315]-hereafter abbreviated to FS315X) not associated with a PPP1R3A gene defect, in unrelated cases of lipodystrophic insulin resistance and show that these mutants inhibit WT receptor action via a non-DNA binding, dominant-negative mechanism.