A novel germline mutation of the LKB1 gene in a patient with Peutz-Jeghers syndrome with early-onset gastric cancer

The gene responsible for Peutz-Jeghers syndrome (PJS), LKB1 (also called STK11) was mapped to chromosome 19p13.3 and was found to encode a putative serine/threonine protein kinase, LKB1. As only a limited number (∼100) of germline mutations of the gene have been reported, and because the protein function is still unclear, information about LKB1 mutations and their expression should be accumulated to understand the phenotype-genotype correlation of this disease. Here we report a patient with sporadic PJS with early-onset gastric cancer. We found a novel germline frameshift mutation (757-758insT) in the LKB1 gene and a marked reduction in LKB1 protein expression in the carcinoma cells, suggesting that the loss of LKB1 function may have led to the carcinogenesis of the gastric cancer.