Linkage of a gene causing familial focal segmental glomerulosclerosis to chromosome 11 and further evidence of genetic heterogeneity.

Focal segmental glomerulosclerosis (FSGS) is a pathological entity characterized by proteinuria, nephrotic syndrome, and the progressive loss of renal function. It is a common cause of end-stage renal disease (ESRD). Recently, familial forms of FSGS have been identified. Two families with autosomal dominant FSGS were evaluated for linkage using 351 genomic microsatellite markers. Linkage, multipoint analysis, and tests for heterogeneity were performed on the subsequent results. In addition, three small families were used for haplotype analysis. Evidence for linkage was found on chromosome 11q21-q22 for the largest family, with a maximum lod score of 9.89. The gene is currently localized to an 18-cM area between flanking markers D11S2002 and D11S1986. The disease in a second family was not linked to this locus or to a previously described locus on chromosome 19q13. There were no shared haplotypes among affected individuals in the three smaller families. Our findings demonstrate that genetic heterogeneity is prevalent in FSGS in that at least three genes cause the FSGS phenotype. Identification of the genes that cause familial FSGS will provide valuable insights into the molecular basis and pathophysiology of FSGS.