Prenatal diagnosis in a hereditary Peutz-Jeghers syndrome family with high cancer risk

Effect of genetic profiling on surgical decisions at hereditary colorectal cancer syndromes

Hereditary colorectal cancer syndromes, such as Lynch syndrome and familial adenomatous polyposis (FAP), present significant clinical challenges due to the heightened cancer risks associated with these genetic conditions. This review explores genetic profiling impact on surgical decisions for hereditary colorectal cancer (HCRC), assessing options, timing, and outcomes. Genotypes of different HCRCs are discussed, revealing a connection between genetic profiles, disease severity, and outcomes. For Lynch syndrome, mutations in the MLH1, MSH2, MSH6, and PMS2 genes guide the choice of surgery. Subtotal colectomy is recommended for patients with mutations in MLH1 and MSH2, while segmental colectomy is preferred for those with MSH6 and PMS2 mutations. In cases of metachronous colon cancer after segmental colectomy, subtotal colectomy with ileorectal anastomosis is advised for all mutations. Surgical strategies for primary rectal cancer include anterior resection or abdominoperineal resection (APR), irrespective of the specific mutation. For rectal cancer occurring after a previous segmental colectomy, proctocolectomy with ileal pouch-anal anastomosis (IPAA) or APR with a permanent ileostomy is recommended. In FAP, surgical decisions are based on genotype-phenotype correlations. The risk of desmoid tumors post-surgery supports a single-stage approach, particularly for certain APC gene variants. Juvenile Polyposis Syndrome (JPS) surgical decisions involve genetic testing, polyp characteristics with attention to vascular lesions in SMAD4 mutation carriers. However, genetic profiling does not directly dictate the specific surgical approach for JPS. In conclusion this review highlights the critical role of personalized surgical plans based on genetic profiles to optimize patient outcomes and reduce cancer risk. Further research is needed to refine these strategies and enhance clinical guidelines.

Two missense STK11 gene variations impaired LKB1/adenosine monophosphate-activated protein kinase signaling in Peutz-Jeghers syndrome

BACKGROUND

Peutz-Jeghers syndrome (PJS) is a rare hereditary neoplastic disorder mainly associated with serine/threonine kinase 11 (STK11/LKB1) gene mutations. Preimplantation genetic testing can protect a patient's offspring from mutated genes; however, some variations in this gene have been interpreted as variants of uncertain significance (VUS), which complicate reproductive decision-making in genetic counseling.

AIM

To identify the pathogenicity of two missense variants and provide clinical guidance.

METHODS

Whole exome gene sequencing and Sanger sequencing were performed on the peripheral blood of patients with PJS treated at the Reproductive and Genetic Hospital of Citic-Xiangya. Software was employed to predict the protein structure, conservation, and pathogenicity of the two missense variation sites in patients with PJS. Additionally, plasmids were constructed and transfected into HeLa cells to observe cell growth. The differences in signal pathway expression between the variant group and the wild-type group were compared using western blot and immunohistochemistry. Statistical analysis was performed using one-way analysis of variance. P < 0.05 was considered statistically significant.

RESULTS

We identified two missense STK11 gene VUS [c.889A>G (p.Arg297Gly) and c.733C>T (p.Leu245Phe)] in 9 unrelated PJS families who were seeking reproductive assistance. The two missense VUS were located in the catalytic domain of serine/threonine kinase, which is a key structure of the liver kinase B1 (LKB1) protein. In vitro experiments showed that the phosphorylation levels of adenosine monophosphate-activated protein kinase (AMPK) at Thr172 and LKB1 at Ser428 were significantly higher in transfected variation-type cells than in wild-type cells. In addition, the two missense STK11 variants promoted the proliferation of HeLa cells. Subsequent immunohistochemical analysis showed that phosphorylated-AMPK (Thr172) expression was significantly lower in gastric, colonic, and uterine polyps from PJS patients with missense variations than in non-PJS patients. Our findings indicate that these two missense STK11 variants are likely pathogenic and inactivate the STK11 gene, causing it to lose its function of regulating downstream phosphorylated-AMPK (Thr172), which may lead to the development of PJS. The identification of the pathogenic mutations in these two clinically characterized PJS patients has been helpful in guiding them toward the most appropriate mode of pregnancy assistance.

CONCLUSION

These two missense variants can be interpreted as likely pathogenic variants that mediated the onset of PJS in the two patients. These findings not only offer insights for clinical decision-making, but also serve as a foundation for further research and reanalysis of missense VUS in rare diseases.

Prenatal Testing for Variants in Genes Associated with Hereditary Cancer Risk: Laboratory Experience and Considerations

Prenatal molecular genetic testing for familial variants that cause inherited disorders has been performed for decades and is accepted as standard of care. However, the spectrum of genes considered for prenatal testing is expanding because of genetic testing for hereditary cancer risk (HCR) and inclusion of conditions with associated cancer risk in carrier screening panels. A few of these disorders, such as ataxia telangiectasia and Bloom syndrome, include increased cancer risk as part of the phenotype, already meet professional guidelines for prenatal testing, and may be associated with increased cancer risk in heterozygous carriers. In addition, recent studies implicate heterozygosity for variants in lysosomal storage disease genes in HCR etiology. Currently, there is no specific professional guidance regarding prenatal testing for HCR. To determine the prevalence of such testing, we reviewed 1345 consecutive prenatal specimens received in our laboratory for familial variant-specific testing and identified 65 (4.8%) with a known or likely HCR component, plus 210 (15.6%) for lysosomal storage disease. These specimens were classified into five distinct categories for clarity and to enable evaluation. Our experience assessing prenatal specimens for variants associated with HCR, with or without a constitutional phenotype, provides metrics for and contributes to the points to consider in prenatal testing for HCR.

Preimplantation genetic testing in two Danish couples affected by Peutz-Jeghers syndrome

BACKGROUND

Guidelines from the European Hereditary Tumor Group as well as The Danish National Guidelines for Peutz-Jeghers Syndrome (PJS) state that both prenatal diagnosis and preimplantation genetic testing for monogenic disorders (PGT-M) should be offered to patients with PJS. However, only a few cases resulting in viable pregnancies have been published.

OBJECTIVE

We present two cases of PJS patients going through PGT-M for PJS. We highlight the awareness of this possibility and discuss the technical and ethical challenges of performing PGT-M for PJS.

METHODS AND RESULTS

Case 1: A 36-year-old male with PJS and his partner were referred for genetic counseling. The patient carried a pathogenic de novo variant in STK11. After a terminated pregnancy of a fetus carrying the same pathogenic variant, microsatellite polymorphic marker analysis was established, and the patient was offered PGT-M. The female partner of the patient gave birth to a healthy boy after five years of fertility treatment. Case 2: A 35-year-old female with PJS and her partner were referred for genetic counseling. She carried an inherited pathogenic STK11 variant. The couple was offered PGT-M. Genetic testing of the embryos was performed using microsatellite polymorphic markers. After two rounds of oocyte extraction a blastocyst predicted not to be affected by PJS was identified. The blastocyst was transferred; however, this did not result in a viable pregnancy.

CONCLUSIONS

PGT-M can be offered to patients with PJS. The process may be long and filled with ethical dilemmas requiring patients to be motivated and persistent.

A novel missense mutation of the STK11 gene in a Chinese family with Peutz-Jeghers syndrome

BACKGROUND

Peutz-Jeghers syndrome (PJS) is a rare autosomal dominant inherited disease caused by mutations in the Serine-Threonine Kinase 11 (STK11) gene. This study aimed to diagnose a Chinese pedigree with PJS and to expand the spectrum of STK11 variants.

METHODS

We performed an inductive analysis of clinical features, gastrointestinal endoscopy, radiologic imaging, and pathological findings in a Chinese family with PJS. Whole-exome sequencing (WES), Sanger sequencing, and STK11 protein 3D structure prediction were performed for establishing a molecular diagnosis.

RESULTS

The proband, her mother, and grandfather presented with pigmentation spots on lips, oral mucosa, and fingers. Her mother and grandfather also had pigmentation spots on face and feet, while her brother had pigmentation spots only on the lower lip. On endoscopy, polyps were discovered in the proband, her mother, and grandfather. A novel heterozygous mutation (c.521A > C) in exon 4 of STK11 was identified in all four patients, leading to a change from histidine to proline in amino acid 174. The variable site p.H174 was highly conserved in different species on multiple sequence alignment analysis.

CONCLUSIONS

We diagnosed a Chinese pedigree with PJS based on clinical features, gastrointestinal endoscopy, and genetic testing results. Our results expanded the spectrum of STK11 variants, which will be helpful for genetic counseling.

Title: Noninvasive prenatal testing of hereditary colorectal cancer syndromes using cell-free DNA in maternal plasma

OBJECTIVE

This study aimed to establish a practical protocol for early noninvasive prenatal testing (NIPT) for fetuses at risk of Peutz-Jeghers syndrome (PJS) or familial adenomatous polyposis (FAP), two classical types of hereditary colorectal cancer syndromes, for risk evaluation and whole-life monitoring.

METHOD

Target enrichment was performed using hybridization probes coordinating the STK11 gene region and APC gene region, with 1,458 highly heterozygous SNPs included. Semitarget amplification random sequencing was used for large fragment deletion detection. For relative haplotype dosage (RHDO) analysis, haplotype construction was performed by SHAPEIT software, the CBS algorithm was used for recombination event calculation, and Bayes factor was used for the determination of whether the fetus was affected.

RESULTS

Haplotypes were successfully constructed in the nine recruited families with different pedigree characteristics, and the results for the RHDO analysis were consistent with the amniocentesis sampling detection results. The cell-free fetal DNA fraction can be detected as low as 2% in maternal plasma.

CONCLUSION

This is the first NIPT assay on hereditary colorectal cancer syndromes based upon RHDO analysis. This article is protected by copyright. All rights reserved.

The Management of Peutz-Jeghers Syndrome: European Hereditary Tumour Group (EHTG) Guideline

The scientific data to guide the management of Peutz–Jeghers syndrome (PJS) are sparse. The available evidence has been reviewed and discussed by diverse medical specialists in the field of PJS to update the previous guideline from 2010 and formulate a revised practical guideline for colleagues managing PJS patients. Methods: Literature searches were performed using MEDLINE, Embase, and Cochrane. Evidence levels and recommendation strengths were assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE). A Delphi process was followed, with consensus being reached when ≥80% of the voting guideline committee members agreed. Recommendations and statements: The only recent guidelines available were for gastrointestinal and pancreatic management. These were reviewed and endorsed after confirming that no more recent relevant papers had been published. Literature searches were performed for additional questions and yielded a variable number of relevant papers depending on the subject addressed. Additional recommendations and statements were formulated. Conclusions: A decade on, the evidence base for recommendations remains poor, and collaborative studies are required to provide better data about this rare condition. Within these restrictions, multisystem, clinical management recommendations for PJS have been formulated.