Genetic heterogeneity in Peutz-Jeghers syndrome

LKB1, the human gene encoding a serine threonine kinase, was recently ident ified as a susceptibility gene for Peutz-Jeghers syndrome (PJS), a disease characterized by the constellation of intestinal hamartomata, oral mucocuta neous hyperpigmentation, and an increased risk for gastrointestinal as well as extraintestinal malignancies. To date, the majority of individuals with PJS have been found to have genetic alterations in LKB1, most of which res ult in protein truncation. Additionally, linkage analyses have suggested a modicum of genetic heterogeneity, with the majority of PJS families showing linkage to the LKB1 locus. In this study, we evaluated five kindreds with greater than two affected family members, five PJS probands with only one o ther affected family member, as well as 23 individuals with sporadic PJS fo r mutations within the LKB1 gene. Conformation sensitive gel electrophoresi s was utilized for the initial screen, followed by direct sequence analysis for characterization. Long-range PCR was used for the detection of larger genetic insertions or deletions. Mutation analysis revealed generic alterat ions in LKB1 in two probands who had a family history of PJS. LKB1 mutation s were detected in only four of the remaining 23 cases of sporadic PJS, The se data suggest the presence of significant genetic heterogeneity for PJS a nd the involvement of other loci in this syndrome. Hum Mutat 16:23-30, 2000 . (C) 2000 Wiley-Liss, Inc.