An atypical presentation of a pathogenic STK11 gene variant in siblings not fulfilling the clinical diagnostic criteria for Peutz-Jeghers Syndrome

Objectives To report an atypical presentation of a pathogenic STK11 gene variant in siblings not fulfilling the clinical diagnostic criteria for Peutz-Jeghers Syndrome (PJS). Case presentation Two siblings presented with prepubertal gynaecomastia and bilateral macro-orchidism, without mucocutaneous pigmentation or gastrointestinal symptoms. There was no family history of PJS. Sibling 1 had unilateral gynaecomastia. Sibling 2 had bilateral gynaecomastia, advanced bone age and bilateral testicular microlithiasis, not indicative of a large-cell calcifying Sertoli cell tumour. Genetics revealed a paternally inherited heterozygous pathogenic STK11 variant (910C>T) in both siblings. The diagnosis was confirmed following the identification of multiple intestinal polyps in their father. Conclusions Prepubertal gynaecomastia and prepubertal macro-orchidism (testicular enlargement without virilisation), always warrant endocrinological investigation, with PJS being an important differential diagnosis. Children may not fulfil the clinical criteria for a diagnosis of PJS at presentation. Genetic testing and gastroenterological investigation of parents may aid diagnosis.

Peutz–Jeghers Syndrome and the Role of Imaging: Pathophysiology, Diagnosis, and Associated Cancers

The Peutz-Jeghers Syndrome (PJS) is an autosomal dominant neoplastic syndrome defined by hamartomatous polyps through the gastrointestinal tract, development of characteristic mucocutaneous pigmentations, and an elevated lifetime cancer risk. The majority of cases are due to a mutation in the STK11 gene located at 19p13.3. The estimated incidence of PJS ranges from 1:50,000 to 1:200,000. PJS carries an elevated risk of malignancies including gastrointestinal, breast, lung, and genitourinary (GU) neoplasms. Patients with PJS are at a 15- to 18-fold increased malignancy risk relative to the general population. Radiologists have an integral role in the diagnosis of these patients. Various imaging modalities are used to screen for malignancies and complications associated with PJS. Awareness of various PJS imaging patterns, associated malignancies, and their complications is crucial for accurate imaging interpretation and patient management. In this manuscript, we provide a comprehensive overview of PJS, associated malignancies, and surveillance protocols.

New Approach for Detection of Normal Alternative Splicing Events and Aberrant Spliceogenic Transcripts with Long-Range PCR and Deep RNA Sequencing

RNA sequencing is a promising technique for detecting normal and aberrant RNA isoforms. Here, we present a new single-gene, straightforward 1-day hands-on protocol for detection of splicing alterations with deep RNA sequencing from blood. We have validated our method’s accuracy by detecting previously published normal splicing isoforms of STK11 gene. Additionally, the same technique was used to provide the first comprehensive catalogue of naturally occurring alternative splicing events of the NBN gene in blood. Furthermore, we demonstrate that our approach can be used for detection of splicing impairment caused by genetic variants. Therefore, we were able to reclassify three variants of uncertain significance: NBN:c.584G>A, STK11:c.863-5_863-3delCTC and STK11:c.615G>A. Due to the simplicity of our approach, it can be incorporated into any molecular diagnostics laboratory for determination of variant’s impact on splicing.

Peutz-Jeghers syndrome: what has been known for 125 years of research? (review)

Peutz-Jeghers syndrome (PJS) is an extremely rare autosomal dominant hereditary disease characterized by the growth of hamartomatous polyps in the gastrointestinal tract, mucocutaneous pigmented macules and an increased risk of malignant neoplasms of various localizations. In most cases the development of PJS is associated with the presence of a mutation in the STK11 gene, but not all patients have this mutation. This review presents the historical aspects of the first data on PJS, considers the clinical manifestations of the disease, current diagnostic methods, as well as recent knowledge about the genetic causes, about the risk of malignant neoplasms in patients with PJS, existing guidelines for screening and treatment of patients with PJS. However, the presence of a number of unresolved issues in genetics, monitoring and treatment indicates the need for further research.

Loss of Stk11 in basolateral amygdalar projection neurons impairs CTA learning by altering the temporal pattern of taste response plasticity in GC

Gustatory cortex (GC) responds to tastes on the tongue with dynamic ensemble activity that represents first the presence, then the identity, and finally the hedonic value (palatability) of tastes. This final state of the taste response is uniquely altered by conditioned taste aversion (CTA) -- a powerful one-trial learning paradigm in which a taste becomes aversive after association with gastric malaise -- a process requiring coordination between GC and basolateral amygdala (BLA). One key requirement for learning in this circuit is expression of the serine/threonine kinase 11 (Stk11) gene (a tumor suppression gene which has only recently been associated with learning). When Stk11 is knocked out in BLA projection neurons (BLApn), CTA learning fails to occur. Here we have examined how learning-related response plasticity in GC taste responses is impacted by the knockout of Stk11 in BLApn. Contrary to the commonly held assumption that a lack of learning means a lack of such plasticity, but consistent with the fact that Stk11KO has been shown to increase the excitability of BLApn, our data reveal that the knockout of Stk11 in BLApn does not eliminate plasticity; rather, it shifts the impact of CTA training on GC taste responses to an earlier, learning-inappropriate epoch. Even naïve taste representations are altered -- specifically, the pattern of similarities and differences among the different taste responses are rendered abnormal by Stk11 KO, and these relationships fail to change with training. Finally, the latency of behavior-related dynamic ensemble features of the GC taste response, which is also abnormal in naïve KO mice, is rendered disorganized by CTA. Together, these results suggest that Stk11 plays a role in governing the coordination of GC activity by BLA, and demonstrate that alterations in the function of BLApn caused by Stk11KO inhibit learning not by inhibiting plasticity but by changing its temporal properties.

Quick and easy: 1-day-protocol for detection of normal alternative splicing events and aberrant spliceogenic transcripts with deep RNA sequencing

RNA sequencing is a promising technique for detecting normal and aberrant RNA isoforms. Here, we present a new single-gene, straightforward 1-day hands-on protocol for detection of splicing alterations with deep RNA sequencing from blood. We have validated our method’s accuracy by detecting all normal splicing isoforms of STK11 gene that were previously published. Additionally, the same technique was used to provide the first comprehensive catalogue of naturally occurring alternative splicing events of the NBN gene in blood. Furthermore, we demonstrate that our approach can be used for detection of splicing impairment caused by genetics variants. Due to the simplicity of our approach it can be incorporated into any molecular diagnostics laboratory for determination of variant’s impact on splicing.

Liver kinase B1 rs9282860 polymorphism and risk for multiple sclerosis in White and Black Americans

We previously reported that a single nucleotide polymorphism (SNP) rs9282860 in serine threoninekinase 11 (STK11) gene which codes for liver kinase B1 (LKB1) has higher prevalence in Whiterelapsing-remitting multiple sclerosis (RRMS) patients than controls. To determine if this SNP is a riskfactor for MS in other populations, we assessed its prevalence in samples collected from AfricanAmerican (AA) persons with MS (PwMS) and controls at multiple Veterans Affairs (VA) Medical Centersand from a network of academic MS centers. There were no significant differences in average age atfirst symptom onset, diagnosis, disease duration, or disease severity between RRMS patients recruitedfrom VAMCs versus non-VAMCs. The SNP was more prevalent in AA than White PwMS, however onlyin secondary progressive MS (SPMS) patients was that difference statistically significant. AA SPMSpatients had higher STK11 SNP prevalence than non-MS controls; and in that cohort the SNP wasassociated with older age at symptom onset and at diagnosis. The results suggest that the STK11 SNPrepresents a risk factor for SPMS in AA patients, and is associated with an older age of symptom onsetand diagnosis.

Implications of Splicing Alterations in the Onset and Phenotypic Variability of a Family with Subclinical Manifestation of Peutz–Jeghers Syndrome: Bioinformatic and Molecular Evidence

Peutz–Jeghers Syndrome (PJS) is an autosomal dominant pre-cancerous disorder caused in 80–90% of cases by germline mutations in the tumor suppressor gene STK11. We performed a genetic test of the STK11 gene in two Italian young sisters suspected of PJS, since they showed pathognomonic café au lait spots in absence of other symptoms and familiarity. Sequencing of all exons of STK11 gene and other 8 genes, suggested to be involved in hamartomatous syndromes, (PTEN, BMPR1A, SDHB, SDHD, SMAD4, AKT1, ENG, PIK3CA) led to the identification in both the probands of a novel germline silent mutation named c.597 G>A, hitting the last nucleotide of exon 4. Interestingly, genetic testing of the two probands’ parents showed that their unaffected father was carrier of this mutation. Moreover, he carried a second intronic substitution named c.465-51 T>C (rs2075606) which was not inherited by his daughters. We also observed that all the family members carrying the c.597 G>A mutation presented an aberrant splice variant of STK11 mRNA lacking exon 4. Furthermore, in silico analysis of c.465-51 T>C substitution showed that it may activate an Enhancer Splicing Element. Finally, qRT-PCR analysis of STK11 expression levels showed a slight downregulation of the wild type allele in the father and a 2-fold downregulation in the probands compared to the unaffected mother. Our results have led the hypothesis that the c.465-51 T>C intronic variant, which segregates with the wild type allele, could increase the splicing effectiveness of STK11 wild-type allele and compensate the side effect of the c.597 G>A splicing mutation, being responsible for the phenotypic variability observed within this family. This finding highlight the importance of RNA analysis in genetic testing, remarking that silent DNA variant can often be splicing variant involved in disease onset and progression. The identification of these variants has a crucial role to ensure an appropriate follow-up and cancer prevention in at-risk individuals.