Correlation between genotype and phenotype in three families with Peutz-Jeghers Syndrome

PeutzJeghers syndrome (PJS) is a hereditary disorder characterized by mucocutaneous pigmentations, gastrointestinal (GI) polyposis and an increased risk of certain malignancies. Little is known about the causative genes of PJS, or their association with the clinical phenotypes of PJS. The present study reports the results of clinical and genetic analysis of three Chinese families with PJS. In addition, the medical histories and clinical manifestations of these families were compared. DNA was collected from the blood samples of patients with PJS and controls. Serine/threonine kinase 11 (STK11), olfactory receptor family 4 subfamily C member 45 (OR4C45) and zonadhesin (ZAN) were amplified by polymerase chain reaction, and analyzed by sequencing and cloning. Two PJSaffected members of one family had a de novo single base deletion (NM_000455.4:c.842delC) in the STK11 gene, and their clinical presentations reflected the quantity of mutant STK11 copies in a dosedependent manner. No pathogenic variants of OR4C45 or ZAN were found in the patients with PJS, although a new single nucleotide polymorphism (NM_003386.2:c.5768delG) of ZAN was identified. The results of the current study identified that a STK11 mutation dosedependent genotypephenotype relationship exists in patients with PJS. In addition, an early onset and high severity of oral pigmentations in PJS was indicative of serious GI phenotypes. These findings may aid the diagnosis and treatment of PJS.