Multidisciplinary management for Peutz-Jeghers syndrome and prevention of vertical transmission to offspring using preimplantation genetic testing

Progress report: Peutz-Jeghers syndrome

Peutz-Jeghers syndrome is a rare, autosomal dominant polyposis syndrome. Presenting with a remarkable phenotype including development of characteristic gastrointestinal polyps, mucocutaneous pigmentations, and an increased risk of cancer, the syndrome has been subject to many studies concerning the natural course of disease. In most patients, pathogenic germline variants are detected in the STK11 gene including cases of mosaicism and structural variants. Yet, studies assessing the effect of surveillance, understanding of cancer development, as well as clinical studies evaluating chemoprevention are lacking. In addition, the impact of Peutz-Jeghers syndrome on mental health, education, and family planning are insufficiently addressed. In this progress report, we describe current knowledge, clinical phenotype, surveillance strategies, and future areas of research.

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.

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 successful case of preimplantation genetic testing for monogenic disorder for aplasia cutis congenita

BACKGROUND

Aplasia cutis congenita (ACC), also called congenital cutaneous hypoplasia, is a serious disease in newborns. Children with ACC often die due to wound infections and bleeding. How the incidence of ACC can be reduced is a question that needs to be solved urgently.

CASE REPORT

We reported a mother who had delivered two children with ACC, both of whom were diagnosed with ACC type VI, skin defects, limb deformities, and congenital heart malformations. One infant died a few days after birth, and another died in utero in the second trimester. Genetic testing in both children showed a heterozygous mutation in the ITGB4 gene [17q25 exon 8, c. 794 dupC, (p. Ala266fs) and exon 15, c. 1860G > A]. The mother later successfully gave birth to a healthy baby using Preimplantation Genetic Testing for Monogenic disorders(PGD-M).

CONCLUSION

The PGD-M technique is highly valuable in reducing the incidence of ACC and improving the prognoses of newborns.