Evidence for genetic heterogeneity in benign familial hematuria

Benign familial hematuria (BFH: MIM141200) is an autosomal-dominant disease accounting for one-fifth of all hematuria of unknown cause in children. Previous observations suggest that BFH may be allelic to recessive Alport syndrome (AS: MIM 203780) with a mutation in the COL4A3/COL4A4 locus. However, it is not clear whether all cases of BFH are due to heterozygous mutation of COL4A3/COL4A4 genes. We report here the exclusion of linkage between BFH and COL4A3/COL4A4 loci at 2q35-37 in a restricted population from Sicily (Italy). Total lod score is –9.6 at theta 0. Furthermore, in some cases exclusion of linkage is evident even considering single families. We conclude that BFH is genetically heterogeneous.