GGTLC1 (gamma-glutamyltransferase light chain 1) is a light chain-encoding locus within the extended GGT gene family localized to chromosome 20 1. While GGTLC1 was originally designated as GGTL6 or GGTLA4, it represents one of two loci encoding only the light chain portion of gamma-glutamyltransferase, distinguishing it from full-length GGT genes 1. According to GO annotations, GGTLC1 participates in protein binding and leukotriene D4 biosynthetic processes, consistent with the GGT family's established role in converting leukotriene LTC4 to LTD4 1. Clinically, GGTLC1 has emerged as a prognostically significant biomarker in cancer. In non-small cell lung cancer (NSCLC), GGTLC1 was integrated into a T cell senescence-related gene signature predictive of patient prognosis and immunotherapeutic sensitivity, with GGTLC1 overexpression suppressing T cell senescence 2. Similarly, in lung adenocarcinoma, GGTLC1 was identified as one of six novel NET-related genes in a prognostic model correlating with clinicopathological and immune traits 3. In lung squamous cell carcinoma, GGTLC1 was identified as a significantly downregulated gene 4. Additionally, GGTLC1 mRNA expression serves as a predictive biomarker for Alzheimer's disease diagnosis with >90% accuracy 5. These findings suggest GGTLC1 functions as a multi-cancer-relevant biomarker with immunomodulatory properties 6.