Disease expression in juvenile polyposis syndrome : a retrospective survey on a cohort of 221 European patients and comparison with a literature-derived cohort of 473 SMAD4/BMPR1A pathogenic variant carriers

Purpose Juvenile polyposis syndrome (JPS) is a rare, autosomal-dominantly inherited cancer predisposition caused in approximately 50% of cases by pathogenic germline variants in SMAD4 and BMPR1A. We aimed to gather detailed clinical and molecular genetic information on JPS disease expression to provide a basis for management guidelines and establish open access variant databases. Methods We performed a retrospective, questionnaire-based European multicenter survey on and established a cohort of SMAD4/BMPR1A pathogenic variant carriers from the medical literature. Results We analyzed questionnaire-based data on 221 JPS patients (126 kindreds) from ten European centers and retrieved literature-based information on 473 patients. Compared with BMPR1A carriers, SMAD4 carriers displayed anemia twice as often (58% vs. 26%), and exclusively showed overlap symptoms with hemorrhagic telangiectasia (32%) and an increased prevalence (39% vs. 13%) of gastric juvenile polyps. Cancer, reported in 15% of JPS patients (median age 41 years), mainly occurred in the colorectum (overall: 62%, SMAD4: 58%, BMPR1A: 88%) and the stomach (overall: 21%; SMAD4: 27%, BMPR1A: 0%). Conclusion This comprehensive retrospective study on genotype-phenotype correlations in 694 JPS patients corroborates previous observations on JPS in general and SMAD4 carriers in particular, facilitates recommendations for clinical management, and provides the basis for open access variant SMAD4 and BMPR1A databases.Peer reviewe

From clinical suspect to molecular confirmation of noonan syndrome; contribution of “best practice” genetic counseling and new technical possibilities

Noonan syndrome (NS) is an autosomal dominant disorder, characterized by variable expressivity of clinical features such as: postnatal growth reduction, congenital heart disease, characteristic facial dysmorphisms and development delay. In ~75% of all NS cases, germline mutations involving RAS-MAPK signaling pathway genes (PTPN11, SOS1, RAF1, KRAS, NRAS, BRAF, SHOC2, MEK1, CBL) are causative. We reported a case of 13-year-old girl [born at 36w by CS (BW 3250 g (~95°), BL 48 cm (~75°)] referred for genetic counseling due to growth retardation, facial dysmorphisms, development delay and learning disability. After birth she presented frequent vomiting, with failure to thrive and at 5 months of age underwent surgery for intestinal malrotation. Because of short stature, Growth Hormone (GH) therapy have been introduced at age of 3yrs up to 11yrs. Negative molecular testing for PTPN11 and SOS1 genes, normal female karyotype and aCGH analysis were observed. Objective examination: H 138 cm, (<3°); W 33 kg, (<3°), no menarche, hypertelorism, eyelids ptosis with down slanting palpebral fissures, low-set and posteriorly rotated ears, high-arched palate, micrognathia, short and webbed neck, low hairline at the back of the neck, pectus excavatum, prominent scoliosis, joint hyperextensibility, bilateral pes planus and mitral valve prolapse disclosed by US. Phenotype of our patient was suggestive to NS, thus further mutational screening has been requested. Missense mutation in exon 2 of KRAS gene (c.40G>A; p.Val14Ile) has been identified. Even though KRAS mutations are usually associated with NS severe phenotype with cardiac involvement (hypertrophic cardiomyopathy), this finding is not present in our patient

The Role of Oxidative Stress in the Pathomechanism of Congenital Malformations

Congenital anomalies are significant causes of mortality and morbidity in infancy and childhood. Embryogenesis requires specific signaling pathways to regulate cell proliferation and differentiation. These signaling pathways are sensitive to endogenous and exogenous agents able to produce several structural changes of the developing fetus. Oxidative stress, due to an imbalance between the production of reactive oxygen species and antioxidant defenses, disrupts signaling pathways with a causative role in birth defects. This review provides a basis for understanding the role of oxidative stress in the pathomechanism of congenital malformations, discussing the mechanisms related to some congenital malformations. New insights in the knowledge of pathomechanism of oxidative stress-related congenital malformations, according to experimental and human studies, represent the basis of possible clinical applications in screening, prevention, and therapies

Accurate classification of NF1 gene variants in 84 Italian patients with neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is one of the most common autosomal dominant genetic diseases. It is caused by mutations in the NF1 gene encoding for the large protein, neurofibromin. Genetic testing of NF1 is cumbersome because 50% of cases are sporadic, and there are no mutation hot spots. In addition, the most recognizable NF1 clinical features—café-au-lait (CALs) spots and axillary and/or inguinal freckling—appear early in childhood but are rather non-specific. Thus, the identification of causative variants is extremely important for early diagnosis, especially in paediatric patients. Here, we aimed to identify the underlying genetic defects in 72 index patients referred to our centre for NF1. Causative mutations were identified in 58 subjects, with 29 being novel changes. We evaluated missense and non-canonical splicing mutations with both protein and splicing prediction algorithms. The ratio of splicing mutations detected was higher than that reported in recent patients’ series and in the Human Gene Mutation Database (HGMD). After applying in silico predictive tools to 41 previously reported missense variants, we demonstrated that 46.3% of these putatively missense mutations were forecasted to alter splicing instead. Our data suggest that mutations affecting splicing can be frequently underscored if not analysed in depth. We confirm that hamartomas can be useful for diagnosing NF1 in children. Lisch nodules and cutaneous neurofibromas were more frequent in patients with frameshifting mutations. In conclusion, we demonstrated that comprehensive in silico analysis can be a highly specific method for predicting the nature of NF1 mutations and may help in assuring proper patient care

Characterization of the rs2802292 SNP identifies FOXO3A as a modifier locus predicting cancer risk in patients with PJS and PHTS hamartomatous polyposis syndromes

Background: Hamartomatous polyposis syndromes (HPS) are inherited conditions associated with high cancer risk. They include the Peutz-Jeghers and the PTEN hamartoma tumor syndromes, which are caused by mutations in the LKB1 and PTEN genes, respectively. Estimation of cancer risk is crucial in order to optimize surveillance, but no prognostic markers are currently available for these conditions. Our study relies on a 'signal transduction' hypothesis based on the crosstalk between LKB1/AMPK and PI3K/PTEN/Akt signaling at the level of the tumor suppressor protein FoxO3A. Interestingly, the FOXO3A rs2802292 G-allele was shown to be associated with longevity, reduced risk of aging-related diseases and increased expression of FoxO3A mRNA. Methods: We typed rs2802292 in 150 HPS unrelated patients and characterized the expression of FoxO3A by quantitative PCR and immunoblot analysis in human intestinal cell lines. Results: We found a significantly higher risk for malignancies in females and TT genotype carriers compared to patients having at least one G-allele. Subgroup analysis for each HPS syndrome revealed a G-allele-associated beneficial effect on cancer risk occurring mainly in males. Molecular characterization of human intestinal cell lines showed that the G-allele significantly correlated with increased basal expression of FoxO3A mRNA and protein. Conclusion: Our results suggest an inverse correlation between the protective allele (G) copy number and cancer risk, and might be useful to optimize surveillance in HPS patients. Further investigations are needed to confirm our hypothesis and to ascertain whether differences in therapeutic response exist across genotypes

Molecular and Functional Characterization of Three Different Postzygotic Mutations in <i>PIK3CA</i>-Related Overgrowth Spectrum (PROS) Patients: Effects on PI3K/AKT/mTOR Signaling and Sensitivity to PIK3 Inhibitors

<div><p>Background</p><p><i>PIK3CA</i>-related overgrowth spectrum (PROS) include a group of disorders that affect only the terminal portion of a limb, such as type I macrodactyly, and conditions like fibroadipose overgrowth (FAO), megalencephaly-capillary malformation (MCAP) syndrome, congenital lipomatous asymmetric overgrowth of the trunk, lymphatic, capillary, venous, and combined-type vascular malformations, epidermal nevi, skeletal and spinal anomalies (CLOVES) syndrome and Hemihyperplasia Multiple Lipomatosis (HHML). Heterozygous postzygotic <i>PIK3CA</i> mutations are frequently identified in these syndromes, while timing and tissue specificity of the mutational event are likely responsible for the extreme phenotypic variability observed.</p><p>Methods</p><p>We carried out a combination of Sanger sequencing and targeted deep sequencing of genes involved in the PI3K/AKT/mTOR pathway in three patients (1 MCAP and 2 FAO) to identify causative mutations, and performed immunoblot analyses to assay the phosphorylation status of AKT and P70S6K in affected dermal fibroblasts. In addition, we evaluated their ability to grow in the absence of serum and their response to the PI3K inhibitors wortmannin and LY294002 <i>in vitro</i>.</p><p>Results and Conclusion</p><p>Our data indicate that patients’ cells showed constitutive activation of the PI3K/Akt pathway. Of note, PI3K pharmacological blockade resulted in a significant reduction of the proliferation rate in culture, suggesting that inhibition of PI3K might prove beneficial in future therapies for PROS patients.</p></div

Clinical and mutational spectrum of the three index cases.

<p><b>a</b> Patient 1, clinically diagnosed with MCAP, showing diffuse capillary malformation at the age of 2 months and cutaneous syndactyly between the 2^nd and 3^rd toes. The <i>PIK3CA</i> c.241 G>A [p.E81K] mutation detected by Sanger sequencing in affected cells and tissues of patient 1 showed varying levels of the mutant allele depending on the tissue tested. The mutation was absent in the patient's blood and in her parents. <b>b</b> Macrodactyly of the right 4^th finger in patient 2, diagnosed with FAO, at the age of 17 years. Sequence of <i>PIK3CA</i> exon 20 in blood and cultured fibroblasts obtained from patient 2 showing that the mutation is undetectable in these samples. <b>c</b> Patient 3, at the age of 15 months before surgical intervention; note the disproportion of the left 2^nd and 3^rd fingers and the subcutaneous mass at the left deltoid region. Sanger sequencing validation of the c.3140 A>T [p.H1047L] mutation detected with targeted deep sequencing in the biopsy from the 2^nd finger of patient 3. <b>d</b> List of samples and mutations detected with targeted deep sequencing. Coverage indicates the mean average of reads on target in the regions of interest (ROI) while frequency denotes the percentage of reads with the mutation.</p