Genetic testing can provide important clinical benefits. Genetic testing has been done for diverse purposes, including the diagnostic testing; presymptomatic and predictive testing and drug-resistance testing. The present study developed genetic testing for two human diseases. Breast cancer is a complex disease that causes approximately 23% of new cancer cases annually. Due to the multifactorial and multiethnicity nature of breast cancer, the identification of the risk alleles for breast cancer in Asian population greatly lags such identification amongst American and European populations, and thus takes on special significance. Concurrently, drug-resistant forms of tuberculosis arising from mutations in the haploidal genome of Mycobacterium tuberculosis is becoming a serious c...[ Read more ]

Genetic testing can provide important clinical benefits. Genetic testing has been done for diverse purposes, including the diagnostic testing; presymptomatic and predictive testing and drug-resistance testing. The present study developed genetic testing for two human diseases. Breast cancer is a complex disease that causes approximately 23% of new cancer cases annually. Due to the multifactorial and multiethnicity nature of breast cancer, the identification of the risk alleles for breast cancer in Asian population greatly lags such identification amongst American and European populations, and thus takes on special significance. Concurrently, drug-resistant forms of tuberculosis arising from mutations in the haploidal genome of Mycobacterium tuberculosis is becoming a serious cause of deaths worldwide. In view of this, in the present study the novel One Label Extension (OLE) method developed by our laboratory has been applied to genotyping the single nucleotide polymorphisms (SNPs) associated with susceptibility to breast cancer in Asia and the SNPs underlying drug resistant tuberculosis. The results showed that, even with the use of just a single-pass OLE genotyping, ≥90% concordance was obtained between the genotype determined using the OLE method and the genotype determined using the more expensive direct DNA sequencing method for nine out of twenty of the breast-cancer associated SNPs, namely No.3 (rs889312), No.5 (rs13281615), No.9 (rs6504950), No.11 (rs10941679), No.12 (rs2046210), No.13 (rs2725362), No.14 (rs4784227), No.17 (rs10484919) and No.18 (rs107543). With drug-resistant tuberculosis, based on phenotyping results obtained from microbiology-based drug susceptibility tests, the sensitivity, specificity and test efficiency estimated for One Label Extension assays were respectively 83.9%, 95.5% and 92.4% with the ropB gene in rifampin resistance, 67.3%, 97.1% and 84.3% with rpsL and rrs in streptomycin resistance, 60.0%, 96.0% and 91.4% with embB in ethambutol resistance, 68.4%, 94.9% and 86.3% with inhA and katG in isoniazid resistance, and 74.1%, 98.9% and 93.2% in multiple drug resistance defined as resistance to at least both isoniazid and rifampin. Upon comparison between the genotype of each target site determined by OLE and the genotype determined by direct DNA sequencing for the PCR amplicons, 100% agreement between the two sets of determinations was obtained for all of the 121 clinical samples. The results showed that the OLE method yielded a rapid, accurate and relatively inexpensive method for detecting drug-resistant M. tuberculosis. These findings suggest that the OLE method can make an important contribution to the analysis of population-wide screening and investigation of disease related genes in the diploidal human genome as well as the haploidal genomes of disease causing microbes.