The STK11 gene was known to be present on chromosome 19 (15,16) and Yoon et al subsequently identified a number of mutation types in this gene, including missense, frame shift, nonsense and splicing site mutations, in 10 PJS patients using polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP; Fig. 1) (17). This evidence concerns the gene STK11 and Peutz-Jeghers syndrome.