Abstract:
Sexual assault is one of the top crimes in Thailand. The examination of rape case specimens take place in laboratory. Currently, the examination begins with acid phosphatase test as a screening test and then confirmed by microscopic examination as a confirmatory test. Both methods were high sensitivity and specificity but the limitations were the likelihood of generating false positive or false negative results. Therefore, to improve the examination of rape case specimens, the objective of this study is to detect male DNA from vaginal fluid samples by Loop-mediated isothermal amplification, which is highly sensitive and reproducible. The primers were designed to be specific to the amelogenin-Y gene and used for detecting male DNA by the LAMP technique. The results showed that the LAMP technique was highly sensitive in detecting male DNA above 0.1 ng with a high specificity to target DNA, it showed positive results only in human male DNA sample but not in human female DNA or animal DNA (mouse, rat, and pig). In addition, when used in rape case samples in Thailand, the results showed that the LAMP technique had a high assay accuracy of 96.7%, which was higher than the acid phosphatase test and microscopic test that had accuracy of 57.6% and 79.3%, respectively and phenol red dye can be used to detect LAMP reaction with naked eyes. The results from this study indicated that the LAMP technique can be used as an alternative method for presumptive test in rape cases.