We are taking three methodologic approaches. First, we are examining known FSGS risk genes or candidate genes, looking for disease-causing mutations and for disease-susceptibility haplotypes. Second, we have undertaken a genome scan, in the African descent population. We may also undertake a whole genome scan in European and Asian descent. Evidence of linkage disequilibrium among these markers will be sought between patients with and without FSGS. Third, when we identify families with multiple affected individuals and which lack known genetic mutations affecting FSGS genes, we will pursue positional cloning.