Folliculin (GENBANK accession# BC015687) was mapped to the BHD locus by a genome wide linkage analysis using polymorphic microsatellite markers in a large Swedish family. They found evidence of linkage to 17p12-q11.2 (Khoo et al., 2001). Subsequent haplotype analysis defined a candidate interval between the two flanking markers, D17S1791 and D17S798 (Khoo et al., 2001).
Schmidt et al. (2001) performed a genome wide scan in a large BHD kindred (172 members) and also localised the gene to the pericentromeric region of 17p using linkage analysis. Two-point linkage analysis of eight additional families with BHD syndrome produced a maximum LOD score of 16.06 at D17S2196. Haplotype analysis identified critical recombinants and defined the minimal region of non-recombination as being within an interval of less than four cM between D17S1857 and D17S805 on chromosome 17p11.2. One additional family, which had histologically confirmed fibrofolliculomas, did not show evidence of linkage to 17p, suggesting genetic heterogeneity.
The FLCN gene was ultimately identified when Nickerson et al. (2002) narrowed the critical region for the BHD locus to a 700-kb segment on 17p11.2. Significantly, this genomic region is associated with a number of diseases (including bladder and breast cancer, Charcot-Marie-Tooth disease and Neurofibromatosis) because of the presence of unstable low-copy number repeat elements.
