T-cell receptor excision circles (TRECs) are small circles of DNA created in T-cells during their passage through the thymus as they rearrange their TCR genes. Their presence indicates maturation of T cells; TRECs are reduced in SCID (Severe combined immunodeficiency disease).
Signal joint T-cell receptor excision circles (sjTRECs) might be used as a way to test the age of the individual from a blood sample. The detection of sjTRECs can be further used as a diagnostic tool to monitor the thymic output (e.g., following hematopoietic stem cell transplantation or in cases of AIDS).
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T-cell receptor excision circles Wikipedia(Text) CC BY-SA