STK11/LKB1 germline mutations in the first Peutz-Jeghers syndrome patients identified in Slovakia

Peutz-Jeghers syndrome (PJS) is characterized by number of hamartomatous polyps in the gastrointestinal tract and by mucocutaneous hypermelanocytic lesions at different sites. Older patients have an increased risk of the cancers of small intestine, stomach, pancreas, colon, esophagus, ovary, testis, uterus, breast and lung. In majority of PJS cases, the germline mutations in serine/threonine kinase STK11/LKB1 gene were found to be associated with disease. Here we report the results of a first mutational screen of STK11/LKB1 in PJS patients characterized in Slovak population. The first patient with unusual carcinoma of duodenum was a sporadic case and carried c.842delC change residing in a mutational C6 repeat hotspot. Neither the polyp nor the tumor of the patient displayed the loss of heterozygosity at the site of mutation suggesting different mechanism involved in the formation of polyp and tumor in this case. The second patient belonged to a three-generation family with typical PJS features but not cancers. Interestingly, the patient displayed concomitant occurrence of adenomatous and hamartomatous polyps. Molecular analysis revealed an IVS2+1A>G mutation that alters the second intron 5' splice site and was shown to lead to aberrant splicing mediated by the U12-dependent spliceosome. The same mutation was present in the 9 affected members of the family but in none of their normal relatives. We also observed novel c. IVS2+61G>A unclassified variant, and recurrent IVS2+24G>T and 3UTR+129C>T polymorphisms. Based on the achieved results, we could offer predictive genetic testing and counseling to other members of the patient's families.