OBJECTIVETo identify the gene causing hereditary multiple exostoses in a Chinese pedigree.

METHODSLinkage analysis was carried out in the family using microsatellite markers on chromosome 8, 11 and 19 respectively. To detect the mutation, the whole coding sequence and the intron-exon boundaries of the candidate gene were amplified and sequenced. The reverse transcriptase-polymerase chain reaction (RT-PCR) was performed to amplify the mutated mRNA.

RESULTSThe disease-causing gene of the family was linked to the EXT2 locus on chromosome 11. A mutation IVS2+1G>A was detected in EXT2 and resulting in 221 bp deletion from 316 to 536 of coding sequence(CDS), which was co-segregated with the disease phenotype. This change led to deletion from codon 106 to codon 178 and subsequent 2 nucleotides, producing a frameshift and truncated protein of 125 aa.

CONCLUSIONThe mutation IVS2+1G>A is the disease-causing mutation in the Chinese pedigree with hereditary multiple exostoses.