Simultaneous analysis of microsatellite instability and loss of heterozygosity by capillary electrophoresis with a homemade kit

Microsatellite instability (MSI) and loss of heterozygosity (LOH), the alteration in length and strength of short tandem repeat sequences are an important molecular characteristic of many human tumors. MSI and LOH analysis has become an attractive method for diagnostic and tumor research purposes. A method for the simultaneous analysis of MSI and LOH at the five microsatellite loci (BAT-26, D17S261, D3S1283, D2S123 and D3S1611) was developed employing a cheap homemade kit to replace the expensive commercial kit on ABI 310 capillary genetic analyzer. After studying the effect of temperature and urea denaturant on microsatellite analysis, 8 mol/L urea and 60 °C were selected for assessing accurately fragment size of microsatellite alleles. Based on this method, 52 sporadic gastric cancers were screened, and MSI and LOH, at least one locus was observed in 15 of 52 (28.8%) patients. Moreover, it is found that a statistically significant association exists between MSI and LOH and tumor-differentiated level.