Abstract: Objective To determine and verify the correlation formula of age estimation using the content of signal joint T-cell receptor excision DNA circle （sjTREC） in human peripheral blood and to discuss its application value in forensic biological practice. Methods The samples of peripheral blood stains were collected from 30 healthy unrelated individuals whose ages were known. The DNAs were extracted from the samples stored at room temperature after 4 weeks. The content of sjTREC was measured by real-time fluorescent quantitative PCR technique, and the TATA box binding protein （TBP） was selected as reference genes. The age of each sample was predicted with the formula which was Age=-7.181 5 Y-42.458±9.42 （Y=dCt_TBP-sjTREC）, and the result was compared with the real age of each individual to determine the accuracy of the formula. Results sjTREC and TBP gene were detectable in all 30 samples of peripheral blood. The contents of sjTREC in human peripheral blood showed a decreasing tendency with aging. The accuracy rate for the age estimation by this method was 76.67%. Conclusion The method for the age estimation with the content of sjTREC was simple, fast, sensitive, and good species specific with important potential application prospect.

Key words: forensic genetics, blood, signal joint T-cell receptor excision DNA circle, age