To identify dysregulated serum factors that could be associated with the inflammatory and arthritic phenotype in MMP-2 deficiency, we first performed a targeted screen on the serum of an 8-year-old male patient with MMP-2 deficiency caused by the inactivating mutation c1294delC (Arg432fs) in the MMP2 gene. Here, MMP2 is linked to hyperinsulinemic hypoglycemia, familial, 4.