Comparison of fluorescent single-strand conformation polymorphism analysisand denaturing high-performance liquid chromatography for detection of EXT1 and EXT2 mutations in hereditary multiple exostoses

EXT1 and EXT2 are two genes responsible for the majority of cases of heredi tary multiple exostoses (HME), a dominantly inherited bone disorder. In ord er to develop an efficient screening strategy for mutations in these genes, we performed two independent blind screens of EXT1 and EXT2 in 34 unrelate d patients with HME using denaturing high-performance liquid chromatography (DHPLC) and fluorescent single-strand conformation polymorphism analysis ( F-SSCP). The mutation likely to cause HME was found in 29 (85%) of the 34pr obands: in 22 of these (76%), the mutation was in EXT1; seven patients (24% ) had EXT2 mutations. Nineteen of these disease mutations have not been pre viously reported. Of the 42 different amplicon variants identified in total in the cohort, 40 were detected by DHPLC and 39 by F-SSCP. This correspond s to mutation detection efficiencies of 95% and 93% respectively. We have a lso found that we can confidently distinguish between different sequence va riants in the same fragment using F-SSCP. but not DHPLC. In light of this, and the similarly high sensitivities of the two techniques, we propose to c ontinue screening with F-SSCP.