Dataset Information

Detection and analysis of common pathogenic germline mutations in Peutz-Jeghers syndrome

ABSTRACT:

BACKGROUND

Different types of pathogenic mutations may produce different clinical phenotypes, but a correlation between Peutz-Jeghers syndrome (PJS) genotype and clinical phenotype has not been found. Not all patients with PJS have detectable mutations of the STK11/LKB1 gene, what is the genetic basis of clinical phenotypic heterogeneity of PJS? Do PJS cases without STK11/LKB1 mutations have other pathogenic genes? Those are clinical problems that perplex doctors.

AIM

The aim was to investigate the specific gene mutation of PJS, and the correlation between the genotype and clinical phenotype of PJS.

METHODS

A total of 24 patients with PJS admitted to the Air Force Medical Center, PLA (formerly the Air Force General Hospital, PLA) from November 1994 to January 2020 were randomly selected for inclusion in the study. One hundred thirty-nine common hereditary tumor-related genes including STK11/LKB1 were screened and analyzed for pathogenic germline mutations by high-throughput next-generation sequencing (NGS). The mutation status of the genes and their relationship with clinical phenotypes of PJS were explored.

RESULTS

Twenty of the 24 PJS patients in this group (83.3%) had STK11/LKB1 gene mutations, 90% of which were pathogenic mutations, and ten had new mutation sites. Pathogenic mutations in exon 7 of STK11/LKB1 gene were significantly lower than in other exons. Truncation mutations are more common in exons 1 and 4 of STK11/LKB1, and their pathogenicity was significantly higher than that of missense mutations. We also found SLX4 gene mutations in PJS patients.

CONCLUSION

PJS has a relatively complicated genetic background. Changes in the sites responsible for coding functional proteins in exon 1 and exon 4 of STK11/LKB1 may be one of the main causes of PJS. Mutation of the SLX4 gene may be a cause of genetic heterogeneity in PJS.

SUBMITTER: Gu G

PROVIDER: S-EPMC8554407 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundPeutz-Jeghers syndrome (PJS) is a rare autosomal dominantly inherited disease resulting in multiple gastrointestinal hamartomatous polyps, mucocutaneous pigmentation, and an increased risk of various types of cancer, and is caused by variations in the serine/threonine protein kinase STK11 (LKB1).MethodsSTK11 gene variations were identified by analyzing STK11 cDNA and genomic DNA. Minigenes carrying the wild-type and mutant sequences were subjected to in vitro splicing assay to dissect the features of these mutations. The different distribution of wild-type and mutant protein in cells were tested by Immunofluorescence assays and the functional analysis of the variation were performed using Western blot.ResultsA novel heterozygous splice-acceptor site variation (c.921-2 A>C) in intron 7 of the STK11 gene which is co-segregates with the PJS phenotypes in the proband and all the affected family members and three previously reported variations (c.180C>G, c.580G>A, c.787_790del) were identified in the four families. The c.921-2 A>C substitution resulted in the inactivation of a splice site and the utilization of a cryptic splice acceptor site surrounding exon 8, generating three different aberrant RNA transcripts, leading to frameshift translation and protein truncation. The results of minigenes indicated that the spliceosome can use a variety of 3' acceptor site sequences to pair with a given 5' donor site. The immunofluorescent visualization showed that the distribution of mutant STK11 was different from that of wild-type STK11, suggesting the mutation may be the causative effect on the dysfunction of the mutant protein. The rescue experiments indicated that the failure of suppressing mTOR phosphorylation by shRNA STK11 could be eliminated by supply of wild-type STK11 rather than mutant STK11.ConclusionWe identified a novel heterozygous mutation (c.921-2 A>C) in the STK11 in a Chinese PJS family. Haploinsufficiency of STK11 might contribute to the pathogenesis of the disease.