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Cirstea I.C.,Heinrich Heine University Dusseldorf | Kutsche K.,Universitatsklinikum Hamburg Eppendorf | Dvorsky R.,Heinrich Heine University Dusseldorf | Gremer L.,Heinrich Heine University Dusseldorf | And 30 more authors.
Nature Genetics | Year: 2010

Noonan syndrome, a developmental disorder characterized by congenital heart defects, reduced growth, facial dysmorphism and variable cognitive deficits, is caused by constitutional dysregulation of the RAS-MAPK signaling pathway. Here we report that germline NRAS mutations conferring enhanced stimulus-dependent MAPK activation account for some cases of this disorder. These findings provide evidence for an obligate dependency on proper NRAS function in human development and growth. © 2010 Nature America, Inc. All rights reserved. Source


Baroni D.,CNR Institute of Biophysics | Zegarra-Moran O.,Unita Operativa di Genetica medica | Moran O.,CNR Institute of Biophysics
Cellular and Molecular Life Sciences | Year: 2014

The cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel is a membrane-integral protein that belongs to the ATP-binding cassette superfamily. Mutations in the CFTR gene cause cystic fibrosis in which salt, water, and protein transports are defective in various tissues. To investigate the conformation of the CFTR in the membrane, we applied the small-angle x-ray scattering (SAXS) technique on microsomal membranes extracted from NIH/3T3 cells permanentely transfected with wild-type (WT) CFTR and with CFTR carrying the ΔF508 mutation. The electronic density profile of the membranes was calculated from the SAXS data, assuming the lipid bilayer electronic density to be composed by a series of Gaussian shells. The data indicate that membranes in the microsome vesicles, that contain mostly endoplasmic reticulum membranes, are oriented in the outside-out conformation. Phosphorylation does not change significantly the electronic density profile, while dephosphorylation produces a significant modification in the inner side of the profile. Thus, we conclude that the CFTR and its associated protein complex in microsomes are mostly phosphorylated. The electronic density profile of the ΔF508-CFTR microsomes is completely different from WT, suggesting a different assemblage of the proteins in the membranes. Low-temperature treatment of cells rescues the ΔF508-CFTR protein, resulting in a conformation that resembles the WT. Differently, treatment with the corrector VX-809 modifies the electronic profile of ΔF508-CFTR membrane, but does not recover completely the WT conformation. To our knowledge, this is the first report of a direct physical measurement of the structure of membranes containing CFTR in its native environment and in different functional and pharmacological conditions. © 2014 Springer Basel. Source


Bonaglia M.C.,Scientific Institute E Medea | Giorda R.,Scientific Institute E Medea | Beri S.,Scientific Institute E Medea | de Agostini C.,Scientific Institute E Medea | And 54 more authors.
PLoS Genetics | Year: 2011

In this study, we used deletions at 22q13, which represent a substantial source of human pathology (Phelan/McDermid syndrome), as a model for investigating the molecular mechanisms of terminal deletions that are currently poorly understood. We characterized at the molecular level the genomic rearrangement in 44 unrelated patients with 22q13 monosomy resulting from simple terminal deletions (72%), ring chromosomes (14%), and unbalanced translocations (7%). We also discovered interstitial deletions between 17-74 kb in 9% of the patients. Haploinsufficiency of the SHANK3 gene, confirmed in all rearrangements, is very likely the cause of the major neurological features associated with PMS. SHANK3 mutations can also result in language and/or social interaction disabilities. We determined the breakpoint junctions in 29 cases, providing a realistic snapshot of the variety of mechanisms driving non-recurrent deletion and repair at chromosome ends. De novo telomere synthesis and telomere capture are used to repair terminal deletions; non-homologous end-joining or microhomology-mediated break-induced replication is probably involved in ring 22 formation and translocations; non-homologous end-joining and fork stalling and template switching prevail in cases with interstitial 22q13.3. For the first time, we also demonstrated that distinct stabilizing events of the same terminal deletion can occur in different early embryonic cells, proving that terminal deletions can be repaired by multistep healing events and supporting the recent hypothesis that rare pathogenic germline rearrangements may have mitotic origin. Finally, the progressive clinical deterioration observed throughout the longitudinal medical history of three subjects over forty years supports the hypothesis of a role for SHANK3 haploinsufficiency in neurological deterioration, in addition to its involvement in the neurobehavioral phenotype of PMS. © 2011 Bonaglia et al. Source


Montagnani M.,University of Bologna | Cazzato S.,Unita Operativa di Pediatria | Mutignani M.,Endoscopia Digestiva ed Interventistica | Cevenini M.,University of Bologna | And 8 more authors.
Clinical Gastroenterology and Hepatology | Year: 2013

Mutations in the gene encoding the cystic fibrosis transmembrane regulator (CFTR) have been reported to increase the risk of recurrent acute pancreatitis in patients with pancreas divisum. We assessed the CFTR gene in a young male patient with pancreas divisum and recurrent acute pancreatitis. Magnetic resonance cholangiopancreatography and computed tomography revealed that the patient had pancreas divisum, with an enlarged and tortuous pancreatic duct; he also had positive results from the cystic fibrosis sweat test. Genetic analysis did not identify any common CFTR mutations, but did show that he was homozygous for the 5T allele in intron 8 IVS8 5T-12TG (which affects splicing at intron 8). Endoscopic sphincterotomy and stenting of papilla minor was performed. The IVS8 5T-12TG variant has been associated with abnormal organ development, therefore it is possible that CFTR has an important role in the development of the pancreatic duct. We propose this patient has recurrent acute pancreatitis resulting from a developmental defect associated with a suboptimal CFTR function. © 2013 AGA Institute. Source


Wenger T.L.,Seattle Childrens Hospital | Harr M.,Seattle Childrens Hospital | Ricciardi S.,Catholic University of the Sacred Heart | Bhoj E.,Seattle Childrens Hospital | And 19 more authors.
American Journal of Medical Genetics, Part A | Year: 2014

Mowat-Wilson syndrome(MWS) is characterized bymoderate to severe intellectual disability and distinctive facial features in association with variable structural congenital anomalies/clinical features including congenital heart disease, Hirschsprung disease, hypospadias, agenesis of the corpus callosum, short stature, epilepsy, andmicrocephaly. Less commonclinical features include ocular anomalies, craniosynostosis, mild intellectual disability, and choanal atresia. These casesmay bemore difficult to diagnose. In this report, we add 28MWS patients withmolecular confirmation of ZEB2 mutation, including seven with an uncommon presenting feature. Among the "unusual" patients, two patients hadclinical featuresof charge syndrome includingchoanalatresia, coloboma, cardiac defects, genitourinary anomaly (1/2), and severe intellectual disability; two patients had craniosynostosis; and three patientshadmildintellectualdisability. Sixteenpatients have previously-unreported mutations in ZEB2. Genotype-phenotype correlations were suggested in those with mild intellectual disability (two had a novel missense mutation in ZEB2, one with novel splice site mutation). This report increases the number of reported patients withMWSwith unusual features, and is the first report of MWS in children previously thought to have CHARGE syndrome. Thesepatients highlight the importance of facialgestalt in the accurate identification ofMWSwhen less common features are present. © 2014 Wiley Periodicals, Inc. Source

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