Novel serine/threonine kinase 11 gene mutations in Peutz-Jeghers syndrome patients and endoscopic management

Phe354Leu polymorphism of the liver kinase B1 gene as a prognostic factor in adult egyptian patients with acute myeloid leukemia

Background

The human liver kinase B1 (LKB1) gene is a significant tumor suppressor widely expressed in all fetal and adult tissues. Despite its established role in solid tumors, the biological and clinical implications of LKB1 gene alterations in hematological malignancies have not been sufficiently recognized.

Aim

This study aimed to determine the frequency of the LKB1 Phe354Leu polymorphism in adult Egyptian patients with cytogenetically normal AML (CN-AML), evaluate its clinical prognostic significance, and investigate its effect on the therapeutic outcome and patient survival.

Methods

Direct sequencing of amplified exon eight of the LKB1 gene was performed to detect the Phe354Leu polymorphism in 72 adult de novo CN-AML patients.

Results

The LKB1 Phe354Leu polymorphism was detected in 16.7% of patients and associated with younger age and lower hemoglobin levels (p < 0.001). Patients in the mutated group had significantly higher total leukocytic count and bone marrow blasts (p = 0.001 and p < 0.001, respectively). The most common FAB subtypes in mutated patients were M4 and M2. The relapse rate was significantly higher in the mutated group (p = 0.004). There was a significant association between the FLT3-ITD polymorphism and LKB1 F354L (p < 0.001). The mutated group had shorter overall survival (p = 0.003). In multivariate analysis, the Phe354Leu polymorphism was a significant independent prognostic variable for the overall and disease-free survival of the studied patients (p = 0.049).

Conclusion

The LKB1 Phe354Leu polymorphism was diagnosed at younger ages in Egyptian CN-AML patients and represented a poor independent prognostic factor in CN-AML. Patients who carried this polymorphism had shorter overall survival and more frequent relapses. Our findings may provide insight into the design of therapeutic targets, and molecular testing of the LKB1 gene is recommended for proper risk stratification of CN-AML patients.

Diagnostic difficulty in Peutz–Jeghers syndrome

A case of diagnostic difficulty facing the patient with colonic polyposis secondary to Peutz–Jeghers syndrome, but without family history and pathognomonic clinical features of the disease, is illustrated. The exams, including biopsy, led to diagnostic uncertainty and the definitive diagnosis was characterized in therapeutic of exception.

Clinical and Genetic Study of Children With Peutz-Jeghers Syndrome Identifies a High Frequency of STK11 De Novo Mutation

OBJECTIVES

The present study aims to identify the genotype-phenotype correlation in children with Peutz-Jeghers Syndrome (PJS) through the analysis of STK11 gene mutations in the context of clinical and pathological characteristics.

METHOD

In this observational cohort study, the clinical characteristics of 18 families diagnosed with pediatric PJS were collected. Genomic DNA from the peripheral blood of affected children and their family members was collected. The coding region of STK11 was amplified by PCR and screened for mutation by Sanger sequencing. The families that were negative for STK11 mutation were further assessed by multiplex ligation-dependent probe amplification (MLPA).

RESULT

Initial presentation in affected children was at 1.6 to 14.2 years and included anemia in 8 patients whereas 6 presented for screening by virtue of family history. All patients underwent endoscopy, colonoscopy, and polypectomy. Polyps were distributed throughout the gastrointestinal (GI) tract, including the small intestine, stomach, colon, and rectum.In the 18 pediatric PJS families, STK11 mutations were detected in 8 families by Sanger sequencing, and large deletions were detected in 3 by MLPA, respectively. Nine of the 11 STK11 mutations were de novo, 3 were novel (c.419T>C:p.L140P, c.314T>G:p.L105X), and (c.488_489insACGG p.L164fs).

CONCLUSIONS

Although the main clinical features of pediatric PJS were similar to those of PJS cases in adults, a high frequency of STK11 de novo mutations were encountered in our population of patients with PJS.

A lesson from a reported pathogenic variant in Peutz-Jeghers syndrome: a case report

Peutz-Jeghers syndrome (PJS) is a rare autosomal dominant disorder characterized by mucocutaneous hyperpigmentation, gastrointestinal (GI) hamartmatous polyps, and an increased risk of various malignancies. Pathogenic variants in the LKB1 tumor suppressor gene (also known as STK11) are the major cause of PJS. In this study, compound heterozygous variants of LKB1, c.890G > A/ c.1062C > G and del(exon1)/ c.1062C > G, were identified in two sporadic Chinese PJS cases respectively. Although all these three variants had been related to the autosomal dominant PJS in previous studies, all evidences collected in this study including de novo data, segregation data, population data, in-silico data, and functional data indicated that del(exon1) and c.890G > A are pathogenic in these two PJS families rather than c.1062C > G. This finding would contribute to genetic counseling for individuals carrying the variant c.1062C > G with or without PJS phenotypes. Moreover, this finding reminds genetic counselors that it is necessary to reevaluate the pathogenicity of reported variants in a known Mendelian disorder in order to avoid a misleading decision.

Clinical characteristics and STK11 gene mutations in Chinese children with Peutz-Jeghers syndrome

Background

Peutz-Jeghers syndrome (PJS) is a rare autosomal dominant inherited disease characterized by gastrointestinal hamartomatous polyps and mucocutaneous melanin spots. Germline mutation of the serine/threonine kinase 11 (STK11) gene are responsible for PJS. In this study, we investigated the clinical characteristics and molecular basis of the disease in Chinese children with PJS.

Methods

Thirteen children diagnosed with PJS in our hospital were enrolled in this study from 2011 to 2015, and their clinical data on polyp characteristics, intussusceptions events, family histories, etc. were described. Genomic DNA was extracted from whole-blood samples from each subject, and the entire coding sequence of the STK11 gene was amplified by polymerase chain reaction and analyzed by direct sequencing.

Results

The median age at the onset of symptoms was 2 years and 4 months. To date, these children have undergone 40 endoscopy screenings, 17 laparotomies and 9 intussusceptions. Polyps were found in the stomach, duodenum, small bowel, colon and rectum, with large polyps found in 7 children. Mutations were found in eleven children, including seven novel mutations (c.481het_dupA, c.943_944het_delCCinsG, c.397het_delG, c.862 + 1G > G/A, c.348_349het_delGT, and c.803_804het_delGGinsC and c.121_139de l19insTT) and four previously reported mutations (c.658C > C/T, c.890G > G/A, c.1062 C > C/G, and c.290 + 1G > G/A). One PJS patient did not have any STK11 mutations.

Conclusions

The polyps caused significant clinical consequences in children with PJS, and mutations of the STK11 gene are generally the cause of PJS in Chinese children. This study expands the spectrum of known STK11 gene mutations.

High-throughput mutation profiling identifies novel molecular dysregulation in high-grade intraepithelial neoplasia and early gastric cancers

BACKGROUND

There is still no widely accepted molecular marker available to distinguish between gastric high-grade intraepithelial neoplasia (HG-IEN) and invasive early gastric cancer (EGC).

METHODS

HG-IEN and EGC lesions coexisting in the same patient were manually microdissected from a series of 15 gastrectomies for EGC; 40 ng DNA was used for multiplex PCR amplification using the Ion AmpliSeq Cancer Panel, which explores the mutational status of hotspot regions in 50 cancer-associated genes.

RESULTS

Of the 15 EGCs, 12 presented at least one somatic mutation among the 50 investigated genes, and 6 of these showed multiple driver gene somatic mutations. TP53 mutations were observed in 9 cases; APC mutations were identified in 3 cases; and ATM and STK11 were mutated in 2 cases. Seven HG-IEN lesions shared an identical mutational profile with the EGC from the same patient; 13 mutations observed in APC, ATM, FGFR3, PIK3CA, RB1, STK11, and TP53 genes were shared by both HG-IEN and ECG lesions. CDKN2A, IDH2, MET, and RET mutations were observed only in EGC. TP53 deregulation was further investigated in an independent series of 75 biopsies corresponding to all the phenotypic lesions occurring in the EGC carcinogenetic cascade. p53 nuclear immunoreaction progressively increased along with the dedifferentiation of the lesions (P < 0.001). Overall, 18 of 20 p53-positive lesions showed a TP53 mutated gene.

DISCUSSION

Our results support the molecular similarity between HG-IEN and EGC and suggest a relevant role for TP53 in the progression to the invasive phenotype and the use of immunohistochemistry as a surrogate to detect TP53 gene mutations.

STK11 gene mutations in patients with Peutz-Jeghers syndrome

AIM: To identify point mutations in the STK11 gene coding region in patients with Peutz-Jeghers syndrome (PJS).

METHODS: The sequences of the coding region of the STK11 gene in 36 PJS patients were analyzed using PCR and DNA sequencing and compared with the normal sequence of the STK11 gene.

RESULTS: Of the 36 patients with PJS, 22 showed STK11 gene mutations in the coding region, including 3 patients having the same mutation and 19 patients with a unique mutation site. The remaining 14 patients were not found to have mutations in the STK11 gene coding region. Of the 22 patients with STK11 gene mutations, 5 showed frame-shift mutations, of which 2 were included in SNP gene databases, and 17 showed missense mutations, of which 8 were changed to a termination codon and 4 were included in SNP gene databases. Among the gene mutations identified in our patients, 15 were not included in gene databases and were considered new mutations. The gene mutation rate was 62.5% in patients with a family history and 60.0% in sporadic cases (P > 0.05).

CONCLUSION: Mutations of the STK11 gene are a major cause of PJS. The newly found missense and frame-shift mutations may be associated with PJS.

Safety of balloon assisted enteroscopy for treatment of small bowel polyps in patients with Peutz-Jeghers syndrome

AIM: To evaluate the safety of polypectomy by balloon assisted enteroscopy (BAE) in patients with Peutz-Jeghers syndrome (PJS).

METHODS: The clinical data for 181 patients with PJS treated at our hospital from April 2004 to July 2014 were analyzed retrospectively, and the related complications of polypectomy by BAE were analyzed.

RESULTS: A total of 483 BAE procedures (285 peroral and 198 peranal) were carried out in 181 PJS patients (101 males and 80 females), and a total of 2680 small intestinal polyps were removed by BAE. The incidence of transient mild abdominal pain and/or abdominal discomfort was 83.2% (397/483). The incidences of perforation, intraoperative hemorrhage and postoperative hemorrhage were 1.4% (7/483), 10.1% (49/483) and 1.9% (9/483), respectively. Acute pancreatitis after operation occurred in one case, and there was no endoscopy related mortality.

CONCLUSION: The overall incidence of complications of polypectomy by BAE in PJS patients is low.

Management of small-bowel polyps at double-balloon enteroscopy

Small bowel tumors (SBTs) are uncommon, insidious in presentation, and frequently represent a diagnostic challenge. The advent of video capsule endoscopy (VCE) and double-balloon endoscopy (DBE) is a significant breakthrough for visual diagnosis of SBTs throughout the small bowel. Contrast-enhanced computed tomography (CECT) and fluoroscopic enteroclysis had significantly lower diagnostic yields of tumors that were 10 mm or smaller in diameter, but VCE and DBE had high diagnostic yields regardless of tumor size. Regarding SBTs larger than 10 mm in diameter, CECT had a significantly lower diagnostic yield of epithelial tumors compared to subepithelial tumors, whereas fluoroscopic enteroclysis and DBE had high diagnostic yields regardless of the tumor type. VCE had a slightly lower diagnostic yield of subepithelial tumors (78%) compared to epithelial tumors. Therefore, a combined examination method by using CECT and VCE is useful for screening of SBTs. In case suspicious of stenosis, patency capsule should be performed to confirm passage before VCE. DBE is useful for further precise examination including biopsy and ultrasonography by using miniature probe, and enteroscopic treatment. After medical, enteroscopic, and surgical treatment, VCE is helpful for follow-up. DBE is safe and useful in resecting the SBTs deep within the small bowel without laparotomy. Indications of enteroscopic resection may be benign tumors regardless of epithelial or subepithelial type, localizing in the mucosal or submucosal layer, which are symptomatic at present or possibly symptomatic or transforming in the future. Malignant tumors localized in the mucosal layer may be indications although detecting at an early stage is challenging. In this review article, we describe management of SBTs/polyps by various modalities.

Spontaneous rupture of a giant gastrointestinal stromal tumor of the jejunum: a case report and literature review

A few cases of a gastrointestinal stromal tumor (GIST) of the small intestine presenting as rupture have been reported in the medical literature. We report an unusual case of a large GIST of the jejunum that presented as a spontaneous rupture. A 70-year-old man was referred to our hospital because of fever and abdominal pain. An abdominal enhanced computed tomography (CT) scan detected a 10-cm tumor with heterogeneous staining, suggesting necrosis or abscess inside the tumor. The patient was treated with antibiotics but inflammation persisted and an operation was performed. Intraoperative findings showed an outgrowing 10-cm mass in the jejunum near Treitz's ligament. The tumor had ruptured with peritoneal metastasis. The solid parenchyma contained a focal area of necrosis within and the small ulcer located in the wall of the jejunum presented a communication with the large tumor cavity. H&E staining showed spindle-shaped cell proliferation, and immunohistochemical staining showed results positive for c-kit and CD34. The patient received a diagnosis of a GIST (high-risk group) of the jejunum and was treated with imatinib mesylate. The patient has remained in good health without recurrence or metastasis one year after the surgical procedure.