Mutations in cardiac troponin I (cTnI) gene were assessed based on gene-chip technology.Special probes were designed to fabricate the low-density gene-chip,which could detect the mutations in exons 3,5,7,and 8 of the cTnI gene simultaneously.For each exon,two oligonucleotide sequences labeled with fluorescein at the 5'-end were designed,one (oligonucleotide Ⅰ) simulating the wild type and the other (oligonucleotide Ⅱ) simulating the mutant.Oligonucleotides Ⅰ and Ⅱ were mixed together to simulate the heterozygote.After optimizing the hybridization protocols,the fabricated gene-chip could detect the mutations in the exons of the cTnI gene with relative high sensitivity and specificity.The fully complementary probe gave a fluorescent signal almost 50% stronger than that of the one-base mismatched one,which is in accordance with the result from a theoretical estimate. An applicable special gene-chip is available to investigate and diagnose familial hypertrophic cardiomyopathy (FHCM) after further improvement.