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Paola Giordano,
Gennaro M Lenato,
Patrizia Suppressa,
Patrizia Lastella,
Franca Dicuonzo,
Luigi Chiumarulo,
Maria Sangerardi,
Paola Piccarreta,
Raffaella Valerio,
Arnaldo Scardapane,
Giuseppe Marano, Nicoletta Resta,
Nicola Quaranta,
Carlo Sabbà
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ABSTRACT: OBJECTIVE: To evaluate the clinical features in a large cohort of pediatric patients with genetically confirmed hereditary hemorrhagic telangiectasia (HHT) and to identify possible predictors of arteriovenous malformation (AVM) onset or clinical significance. STUDY DESIGN: Prospective cross-sectional survey of all children subjected to screening for AVMs in the multidisciplinary HHT center. All patients proved to be carriers of endoglin mutations or activin A receptor type-II-like kinase 1 mutations, defined as HHT1 and HHT2, respectively. A full clinical-radiological protocol for AVM detection was adopted, independent from presence or absence of AVM-related symptoms. RESULTS: Forty-four children (mean age, 10.3 years; range, 1-18) were subjected to a comprehensive clinical-radiologic evaluation. This investigation disclosed cerebrovascular malformations in 7 of 44 cases, pulmonary AVMs in 20 of 44 cases, and liver AVMs in 23 of 44 cases. Large visceral AVMs were found in 12 of 44 children and were significantly more frequent in patients with HHT1. Only large AVMs were associated with symptoms and complications. CONCLUSIONS: Children with HHT have a high prevalence of AVMs; therefore, an appropriate clinical and radiological screening protocol is advisable. Large AVMs can be associated with complications in childhood, whereas small AVMs probably have no clinical risk.
The Journal of pediatrics 03/2013; · 4.02 Impact Factor
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Nicoletta Resta,
Daniela Pierannunzio,
Gennaro Mariano Lenato,
Alessandro Stella,
Riccardo Capocaccia,
Rosanna Bagnulo,
Patrizia Lastella,
Francesco Claudio Susca,
Cristina Bozzao,
Daria Carmela Loconte, [......],
Laura Giunti,
Vittoria Stigliano,
Liliana Varesco,
Lucio Bertario,
Maurizio Genuardi,
Emanuela Lucci Cordisco,
Maria Grazia Tibiletti,
Carmela Di Gregorio,
Angelo Andriulli,
Maurizio Ponz de Leon
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ABSTRACT: BACKGROUND: Germline mutations in the STK11/LKB1 gene cause Peutz-Jeghers syndrome, an autosomal-dominantly inherited condition characterized by mucocutaneous pigmentation, hamartomatous gastrointestinal polyposis, and an increased risk for various malignancies. We here report the results of the first Italian collaborative study on Peutz-Jeghers syndrome. AIMS: To assess cancer risks in a large homogenous cohort of patients with Peutz-Jeghers syndrome, carrying, in large majority, an identified STK11/LKB1 mutation. METHODS: One-hundred and nineteen patients with Peutz-Jeghers syndrome, ascertained in sixteen different Italian centres, were enrolled in a retrospective cohort study. Relative and cumulative cancer risks and genotype-phenotype correlations were evaluated. RESULTS: 36 malignant tumours were found in 31/119 (29 STK11/LKB1 mutation carriers) patients. The mean age at first cancer diagnosis was 41 years. The relative overall cancer risk was 15.1 with a significantly higher risk (p<0.001) in females (22.0) than in males (8.6). Highly increased relative risks were present for gastrointestinal (126.2) and gynaecological cancers (27.7), in particular for pancreatic (139.7) and cervical cancer (55.6). The Kaplan-Meier estimates for overall cumulative cancer risks were 20%, 43%, 71%, and 89%, at age 40, 50, 60 and 65 years, respectively. CONCLUSION: Peutz-Jeghers syndrome entails markedly elevated cancer risks, mainly for pancreatic and cervical cancers. This study provides a helpful reference for improving current surveillance protocols.
Digestive and Liver Disease 02/2013; · 3.05 Impact Factor
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ABSTRACT: Molecular testing for KRAS and BRAF mutations in tumor tissue is a fundamental tool to identify patients with metastatic colorectal cancer (CRC) who are eligible for anti-EGFR monoclonal antibody therapy. We here report a molecular analysis by high-resolution melting analysis and direct sequencing of KRAS, BRAF and PIK3CA hot spot mutations in 209 Italian CRC patients. One hundred and ten patients (51%) were identified who were potentially nonresponders to anti-EGFR therapy: 90/209 patients (43%) harboring KRAS mutations, 13/117 (11.1%) with the V600E BRAF mutation, and 7/209 (3.3%) with mutations in PIK3CA exon 20. The prevalence of BRAF and PIK3CA mutations was significantly higher in patients older than 65 years (p=0.014 and p=0.018), while patients with triple-negative tumors were significantly younger than mutation carriers (p=0.000011). Patients with gene mutations also showed a trend towards preferential tumor location in the colon (p=0.026). Moreover, although involving a relatively small number of samples, we report the presence of a discordant mutational profile between primary tumors and secondary lesions (3/9 patients), suggesting that it is worthwhile to test other available tissues in order to better define the efficacy of targeted therapy. Further correlations of specific clinical features with tumor mutational profile could be helpful to predict the response of CRC patients to monoclonal antibody therapy.
The International journal of biological markers 11/2012; · 1.48 Impact Factor
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ABSTRACT: Background: Birth defects are very common, affecting two to three infants in every 100 births, and often represent a diagnostic and management challenge. The birth of a child with multiple malformations is the beginning of a complex diagnostic process, where the primary purpose is to determine a precise nosological definition. An accurate diagnosis is a key prerequisite in providing a care plan, a prognosis and genetic counselling. The poor specificity of birth defects, the aetiology and course of which can vary despite similar phenotypic patterns, often makes the diagnostic path problematic. The advent and application of high-resolution chromosomal microarray, encompassing array-based comparative genome hybridization and single-nucleotide polymorphism arrays, has led to the detection of genomic copy-number abnormalities in patients affected by multiple congenital anomalies, dysmorphisms, developmental delay and mental retardation, but who have a normal karyotype. Aim: We discuss current guidelines and recommendations for chromosomal microarray use and how its application can help clinicians make accurate diagnoses in order to appropriately manage and treat affected newborns. Conclusions: Current guidelines strongly support the application of chromosomal microarray analysis as a first-tier cytogenetic diagnostic test alternative to karyotyping for patients with multiple congenital anomalies, or developmental delay, intellectual disability and autism spectrum disorders.
The journal of maternal-fetal & neonatal medicine: the official journal of the European Association of Perinatal Medicine, the Federation of Asia and Oceania Perinatal Societies, the International Society of Perinatal Obstetricians 10/2012; 25 Suppl 4:116-8. · 1.36 Impact Factor
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Paola Pierucci,
Gennaro M Lenato,
Patrizia Suppressa,
Patrizia Lastella,
Vincenzo Triggiani,
Raffaella Valerio,
Mario Comelli,
Daniela Salvante,
Alessandro Stella, Nicoletta Resta,
Giancarlo Logroscino,
Francesco Resta,
Carlo Sabbà
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ABSTRACT: The difficulty in establishing a timely correct diagnosis is a relevant matter of concern for several rare diseases. Many rare-disease-affected patients suffer from considerable diagnostic delay, mainly due to their poor knowledge among healthcare professionals, insufficient disease awareness among patients' families, and lack of promptly available diagnostic tools. Hereditary Haemorrhagic Telangiectasia (HHT) is an autosomal-dominantly inherited vascular dysplasia, affecting 1:5,000-10,000 patients. HHT is characterized by high variability of clinical manifestations, which show remarkable overlapping with several common diseases.
To perform a detailed analysis concerning the diagnostic time lag occurring in patients with HHT, defined as the time period spanning from the first clinical manifestation to the attainment of a definite, correct diagnosis.
A questionnaire was administered to the HHT patients previously recruited from 2000 and 2009. Clinical onset, first referral to a physician for disease manifestations, and first correct diagnosis of definite HHT were collected. Eventual misdiagnosis at first referral and serious complications occurring throughout the time elapsing between disease onset and definite diagnosis were also addressed.
In the 233 respondents, the clinical onset of disease occurred at an age of 14.1 yrs, while the age of first referral and the age of first definite diagnosis of HHT were 29.2 yrs and 40.1 yrs, respectively. Only 88/233 patients received a correct diagnosis at first counseling. Thus, the diagnostic time lag, represented by the time elapsing from disease onset and first definite diagnosis of HHT, proved to be 25.7 yrs. Twenty-two patients suffered from severe complications during this time interval. The diagnostic delay was significantly longer (p < 0.001) in index patients (first patients who attained definite HHT diagnosis in a given family) than in non-index patients (relative of index patients). The diagnostic time lag was also significantly associated with education grade (p < 0.001).
Our data report for the first time a systematic inquiry of diagnostic delay in HHT showing that patients receive a definite diagnosis only after nearly three decades from disease onset. Concerted efforts are still to be made to increase awareness of this disease among both families and physicians.
Orphanet Journal of Rare Diseases 06/2012; 7:33. · 5.83 Impact Factor
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Vincenzo Triggiani,
Edoardo Guastamacchia,
Giuseppina Renzulli,
Vito Angelo Giagulli,
Emilio Tafaro,
Brunella Licchelli,
Francesco Resta,
Carlo Sabbà,
Rosanna Bagnulo,
Patrizia Lastella,
Alessandro Stella, Nicoletta Resta
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ABSTRACT: Peutz-Jeghers syndrome (PJS) is a rare dominantly inherited disease characterized by the association of gastrointestinal hamartomatous polyposis, mucocutaneous hyperpigmentation, and increased risk of cancer at different target organs. Its occurrence with differentiated thyroid cancer, particularly papillary thyroid carcinoma (PTC), even if rare, has been described.
We here present a case of PTC observed in a PJS patient and a review of the literature aiming at discussing the utility of thyroid surveillance in the management of these patients. A 22-year-old woman presenting with hyperpigmented lesions of the lips and hamartomatous polyps in the stomach, duodenum, jejunum, and ileum, leading to the suspicion of PJS, was submitted to genetic analysis. Mutation scanning of the Liver Kinase B1 (LKB1) gene identified the presence of the truncating mutation E265X, thus confirming the clinical diagnosis. Beside the endoscopic, radiologic, and echographic evaluations required by the standard surveillance guidelines, the patient had a neck ultrasound (US), which showed a 5×4×6 mm hypoechoic nodule in the right thyroid lobe. The nodule contained microcalcifications and a perinodular vascular pattern. The cytological preparations derived from US-guided fine-needle aspiration biopsy of the nodule demonstrated the presence of PTC. The patient underwent a video-assisted total thyroidectomy and the histological examination revealed a follicular variant of papillary microcarcinoma. Radioactive iodine therapy was not performed because of the small size of the lesion. The patient was started on levothyroxine therapy to keep the serum thyrotropin levels suppressed. Both the sequencing and the multiplex ligation-dependent probe amplification analysis could not identify any LKB1 mutation in the tumor specimen, and the methylation-specific polymerase chain reaction assay excluded hypermethylation of the LKB1 promoter as the mechanism of inactivation for the remaining normal allele in the tumor.
Although other mechanisms of LKB1 silencing may be responsible for its inactivation in the thyroid cancer, we cannot rule out that the occurrence of thyroid carcinoma could be a coincidental finding in this patient. However, the case here presented suggests that US of the thyroid could possibly become an integral part of the evaluation and the follow-up program adopted for PJS patients.
Thyroid: official journal of the American Thyroid Association 08/2011; 21(11):1273-7. · 2.60 Impact Factor
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ABSTRACT: In patients with Lynch syndrome, germline mutations in DNA mismatch repair (MMR) genes cause a high risk of developing a broad spectrum of cancers. To date, the management of patients with Lynch syndrome has represented a major challenge because of large variations in age at cancer onset. Several factors, including genetic anticipation, have been proposed to explain this phenotypic heterogeneity, but the molecular mechanisms remain unknown. Telomere shortening is a common event in tumorigenesis and also has been observed in different familial cancers. In this study, the authors investigated the possibility of a relation between telomere length and cancer onset in patients with Lynch syndrome.
The mean telomere length was measured using quantitative polymerase chain reaction in peripheral blood samples from a control group of 50 individuals, from 31 unaffected mutation carriers, and from 43 affected patients, and the results were correlated with both gene mutation and cancer occurrence. In affected patients, telomere attrition was correlated with age at cancer onset. In all patients, a t test was used to assess the linearity of the regression.
A significant correlation between telomere length and age was observed in both affected and unaffected mutation carriers (P = .0016 and P = .004, respectively) and in mutS homolog 2 (MSH2) mutation carriers (P = .0002) but not in mutL homolog 1 (MLH1) mutation carriers. Telomere attrition was correlated significantly with age at onset in MSH2 carriers (P = .004), whereas an opposite trend toward longer telomeres in patients with delayed onset was observed in MLH1 carriers.
The current data suggested that telomere dynamics differ between MLH1 and MSH2 mutation carriers. It is possible that subtle, gene-specific mechanisms can be linked to cancer onset and anticipation in patients with Lynch syndrome.
Cancer 03/2011; 117(18):4325-35. · 4.77 Impact Factor
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ABSTRACT: Peutz-Jeghers syndrome (PJS) is a rare, dominantly inherited disorder characterized by gastrointestinal hamartomatous polyps, mucocutaneous hyperpigmentation, and an increased risk of cancer. We present a 16-month-old child diagnosed with PJS, who had distinguishing features compared with the previously reported cases with respect to her clinical presentation, associated malignancies, and genetic analysis. To our knowledge, this is the first report of adrenocortical carcinoma in association with PJS, as well as the first instance of associated thyroid cancer in a child with PJS. We briefly review the relevant literature and highlight the recent progress achieved in the investigation of the syndrome.
Journal of Pediatric Surgery 03/2011; 46(3):570-3. · 1.45 Impact Factor
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Patrizia Lastella,
Margherita Patruno,
Giovanna Forte,
Alba Montanaro,
Carmela Di Gregorio,
Carlo Sabbà,
Patrizia Suppressa,
Adalgisa Piepoli,
Anna Panza,
Angelo Andriulli, Nicoletta Resta,
Alessandro Stella
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ABSTRACT: Lynch syndrome (LS), or hereditary non-polyposis colorectal cancer (HNPCC), is an autosomal dominant condition responsible for early onset cancer mostly in the colonrectum and endometrium as well as in other organ sites. Lynch syndrome is caused by germline mutations in mismatch repair genes, prevalently in hMSH2, hMLH1, and less frequently in hMSH6 and hPMS2. Twenty-nine non-related index cases with colorectal cancer (CRC) were collected from a region in southeast Italy (Apulia). Among this set of patients, fifteen fulfilled the Amsterdam criteria II. The presence of tumor microsatellite instability (MSI) was assessed in all index cases and 19 (15 AC+/4 AC-) were classified as MSI-H. Mutation analysis performed on all patients, identified 15 pathogenic mutations in hMLH1 and 4 in hMSH2. 4/15 mutations in hMLH1 and 2/4 hMSH2 mutations have not been previously reported. Three previously reported mutations were further investigated for the possibility of a common founder effect. Genetic counseling was offered to all probands and extended to 183 relatives after molecular testing and 85 (46%) mutation carriers were identified. Eighty mutation carriers underwent an accurate clinical and instrumental surveillance protocol. Our results confirm that the identification of LS patients based exclusively on family history may miss patients carrying germline mutations in the MMR genes. Moreover, our results demonstrated that molecular screening and subsequent instrumental surveillance are very effective in identifying CRCs at earlier stages and reducing the number of deaths from secondary cancers in HNPCC patients.
Familial Cancer 02/2011; 10(2):285-95. · 1.30 Impact Factor
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Nicoletta Resta,
Roberto Giorda,
Rosanna Bagnulo,
Silvana Beri,
Erika Della Mina,
Alessandro Stella,
Marilidia Piglionica,
Francesco Claudio Susca,
Ginevra Guanti,
Orsetta Zuffardi,
Roberto Ciccone
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ABSTRACT: The Peutz-Jeghers Syndrome (PJS) is an autosomal dominant polyposis disorder with increased risk of multiple cancers. STK11/LKB1 (hereafter named STK11) germline mutations account for the large majority of PJS cases whereas large deletions account for about 30% of the cases. We report here the first thorough molecular characterization of 15 large deletions identified in a cohort of 51 clinically well-characterized PJS patients. The deletions were identified by MLPA analysis and characterized by custom CGH-array and quantitative PCR to define their boundaries. The deletions, ranging from 2.9 to 180 kb, removed one or more loci contiguous to the STK11 gene in six patients, while partial STK11 gene deletions were present in the remaining nine cases. By means of DNA sequencing, we were able to precisely characterize the breakpoints in each case. Of the 30 breakpoints, 16 were located in Alu elements, revealing non-allelic homologous recombination (NAHR) as the putative mechanism for the deletions of the STK11 gene, which lays in a region with high Alu density. In the remaining cases, other mechanisms could be hypothesized, such as microhomology-mediated end-joining (MMEJ) or non-homologous end-joining (NHEJ). In conclusion we here demonstrated the non-random occurrence of large deletions associated with PJS. All our patients had a classical PJS phenotype, which shows that haploinsufficiency for SBNO2, C19orf26, ATP5D, MIDN, C19orf23, CIRBP, C19orf24,and EFNA2, does not apparently affect their clinical phenotype.
Human Genetics 10/2010; 128(4):373-82. · 5.07 Impact Factor
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ABSTRACT: Familial adenomatous polyposis is a rare autosomal dominant inherited disease (incidence, 1/8000). More than 90% of families affected by familial adenomatous polyposis have a mutation in the tumor suppressor gene adenomatous polyposis coli (APC). Mutations in this gene are characterized by 100% penetrance, although there is a variation in phenotypic expression of the disease. According to a 2004 survey of the Italian Human Genetic Society, about 264 APC gene molecular genetic tests were performed by Italian laboratories per year. The Italian External Quality Assessment (IEQA), financially supported by the Ministry of Health and coordinated by the Istituto Superiore di Sanità, was started in 2000 to improve the quality of molecular genetic tests in Italy. In the frame of the IEQA, about 50% of public laboratories performing APC gene tests have been monitored. The number of responding public laboratories during the 5 years was 6, 7, 7, 7, and 5 from 2001 to 2006, respectively; on average, 96.3% of samples completely analyzed were correctly genotyped. Methods used by laboratories to detect mutation were direct sequencing, single-strand conformation polymorphism, protein truncation test, and denaturing high-performance liquid chromatography. Written reports were not homogeneous among laboratories, although a new form of written report was proposed to laboratories in 2004. It will be interesting to monitor the effects of the reporting model and the output of this educational action in the future.
Genetic Testing and Molecular Biomarkers 02/2010; 14(2):175-81. · 1.11 Impact Factor
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ABSTRACT: Ganglioglioma is a primary central nervous system low-grade tumor composed of mixed populations of glial and neuroepithelial elements.
The authors report a case of ganglioglioma in a patient affected by Peutz-Jeghers syndrome, an autosomal dominant disease with varying expressions and incomplete penetrance responsible for an increased risk of gastrointestinal and other malignant tumor forms.
The polymerase chain reaction products of exon 6 of STK11/LKB1 showed an abnormal pattern in the single-strand conformation polymorphism analysis. Further sequencing analysis of the exon 6 identified a deletion of T and an insertion of AC at nucleotide 821 causing a shift of the reading frame. The same mutation was found in the patient's peripheral blood. The ribonucleic acid analysis on the ganglioglioma cells revealed an out-of-frame STK11 isoform, characterized by an exon 4 skipping, which resulted in nonsense mediated decay sensitive.
This report details the molecular genetic analysis of a ganglioglioma that allowed the identification of a new mutation.
Neurosurgery 12/2008; 63(5):976-80; discussion 980. · 2.79 Impact Factor
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ABSTRACT: In a previously published article (Resta et al., 2006) on Robert's syndrome in prenatal diagnosis, a case of a 36-year-old woman and her 36-year-old, nonconsanguineous husband were presented. Our findings suggest the existence of nonsense mediated decay (NMD) variability which could account for the varying severity reported in carriers of identical mutations. Furthermore, fetal cells were used to evaluate the influence of premature centromere separation (PCS) on the sister chromatid exchange (SCE) and micronucleus (MN) frequency. Given the similar variation observed in the SCE frequencies, dependent on tissue/cell type (amniotic fluid sample, chorionic villus sampling) and duration of in vitro cultures (48 hours or 72 hours), the idea was that this new piece of information could be interesting. It seems that the SCE frequency increased proportionally to the cell cycle increasing (1 degrees < 2 degrees < 3 degrees ... n). Obviously, our observations are too scarce to draw conclusions, but further investigation could be useful to corroborate or dispute these results, considering that the two techniques, (MN and SCE), are simple to perform and do not require expensive laboratory equipment.
Twin Research and Human Genetics 09/2007; 10(4):655-7. · 1.70 Impact Factor
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Hamid Mehenni, Nicoletta Resta,
Ginevra Guanti,
Louisa Mota-Vieira,
Aaron Lerner,
Mohammed Peyman,
Kim A Chong,
Larbi Aissa,
Ali Ince,
Angel Cosme,
Michael C Costanza,
Colette Rossier,
Uppala Radhakrishna,
Randall W Burt,
Didier Picard
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ABSTRACT: Germline mutations of the tumor suppressor gene LKB1/STK11 are responsible for the Peutz-Jeghers syndrome (PJS), an autosomal-dominant disorder characterized by mucocutaneous pigmentation, hamartomatous polyps, and an increased risk of associated malignancies. In this study, we assessed the presence of pathogenic mutations in the LKB1/STK11 gene in 46 unrelated PJS families, and also carried genotype-phenotype correlation in regard of the development of cancer in 170 PJS patients belonging to these families. All LKB1/STK11 variants detected with single-strand conformational polymorphism were confirmed by direct sequencing, and those without LKB1/STK11 mutation were further submitted to Southern blot analysis for detection of deletions/rearrangements. Statistical analysis for genotype-phenotype correlation was performed. In 59% (27/46) of unrelated PJS cases, pathogenic mutations in the LKB1/STK11 gene, including 9 novel mutations, were identified. The new mutations were 2 splice site deletion-insertions, 2 missenses, 1 nonsense, and 4 abnormal splice sites. Genotype-phenotype analysis did not yield any significant differences between patients carrying mutations in LKB1/STK11 versus those without mutations, even with respect to primary biliary adenocarcinoma. This study presents the molecular characterization and cancer occurrence of a large cohort of PJS patients, increases the mutational spectrum of LKB1/STK11 allelic variants worldwide, and provides a new insight useful for clinical diagnosis and genetic counseling of PJS families.
Digestive Diseases and Sciences 08/2007; 52(8):1924-33. · 2.12 Impact Factor
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American Journal of Medical Genetics Part A 04/2007; 143(5):518-20. · 2.39 Impact Factor
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ABSTRACT: Roberts syndrome (RS) is a rare disorder characterized by tetraphocomelia and several other clinical features. Cells from RS patients exhibit characteristic premature separation of heterochromatic region of many chromosomes and abnormalities in cell cycle. Mutations in the ESCO2 gene have recently been identified in 20 RS families. We performed mutational analysis of the ESCO2 gene in two fetuses diagnosed with RS and their normal parents. In both fetuses, we identified homozygosity for the c. 745_746delGT mutation, while the non-consanguineous parents were both heterozygous for the same mutation. Considering the position of the mutation identified, we carried out qualitative and quantitative real-time ESCO2 cDNA analysis on RNA isolated from CVS-stromal cells in one fetus, amniocytes in the second fetus, and lymphocytes from the heterozygous parents. The results of this analysis showed that despite the presence of a premature termination codon (PTC) 112 nucleotides upstream of the next exon3-exon4 junction, the mutant ESCO2 mRNA was present in both fetuses, albeit at low levels, indicating a partial resistance to nonsense mediated decay (NMD). Interestingly, when cells derived from the two fetuses were treated with an inhibitor of translation, they revealed the presence of tissue and individual variability in NMD efficiency, despite the identical mutational status. The existence of such a variation in the NMD efficiency could explain the broad intrafamilial and interfamilial variability in the clinical presentation of RS patients, and in other genetic diseases where nonsense mutations are responsible for most of the mutation load. Moreover, considering that a mutated full length mRNA was produced in both fetuses, we used Western blot analysis to demonstrate the absence of the ESCO2-truncated protein in cells derived from both fetuses and in a lymphoblastoid cell line derived from the parents.
Journal of Cellular Physiology 11/2006; 209(1):67-73. · 3.87 Impact Factor
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ABSTRACT: The Peutz-Jeghers syndrome (PJS), an autosomal dominant disorder caused by inactivating germline mutations in the serine-threonine kinase gene LKB1, is characterized by mucocutaneous pigmentation, multiple gastrointestinal hamartomatous polyps, and by an increased risk for developing tumors involving several different organs. To date, no brain tumors have been described in PJS patients. In this report, we describe a case of ganglioglioma in a 22-year-old PJS patient. Single-strand conformation polymorphism-Heteroduplex analysis evidenced an abnormal pattern in exon 6 of the LKB1 gene. Sequencing revealed a 821delTinsAC mutation creating a termination codon 29 nucleotides downstream (p.Asn274fsX11). RNA studies showed an out-of-frame LKB1 isoform derived from the wild type allele and generated by exon 4 skipping. Since the LKB1 gene is expressed in the fetal and adult brain, our data would suggest its likely involvement in the pathogenesis of a subset of gangliogliomas.
Acta Neuropathologica 08/2006; 112(1):106-11. · 9.32 Impact Factor
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ABSTRACT: Hereditary haemorrhagic telangiectasia (HHT or Rendu-Osler-Weber syndrome) is an autosomal dominant disorder characterized by localized angiodysplasia due to mutations in endoglin, ALK-1 gene, and a still unidentified locus. The lack of highly recurrent mutations, locus heterogeneity, and the presence of mutations in almost all coding exons of the two genes makes the screening for mutations time-consuming and costly. In the present study, we developed a DHPLC-based protocol for mutation detection in ALK1 and ENG genes through retrospective analysis of known sequence variants, 20 causative mutations and 11 polymorphisms, and a prospective analysis on 47 probands with unknown mutation. Overall DHPLC analysis identified the causative mutation in 61 out 66 DNA samples (92.4%). We found 31 different mutations in the ALK1 gene, of which 15 are novel, and 20, of which 12 are novel, in the ENG gene, thus providing for the first time the mutational spectrum in a cohort of Italian HHT patients. In addition, we characterized the splicing pattern of ALK1 gene in lymphoblastoid cells, both in normal controls and in two individuals carrying a mutation in the non-invariant -3 position of the acceptor splice site upstream exon 6 (c.626-3C>G). Functional essay demonstrated the existence, also in normal individuals, of a small proportion of ALK1 alternative splicing, due to exon 5 skipping, and the presence of further aberrant splicing isoforms in the individuals carrying the c.626-3C>G mutation.
Human Mutation 03/2006; 27(2):213-4. · 5.69 Impact Factor
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ABSTRACT: Abnormalities of pre-mRNA splicing are increasingly recognized as an important mechanism through which gene mutations cause disease. However, apart from the mutations in the donor and acceptor sites, the effects on splicing of other sequence variations are difficult to predict. Loosely defined exonic and intronic sequences have been shown to affect splicing efficiency by means of silencing and enhancement mechanisms. Thus, nucleotide substitutions in these sequences can induce aberrant splicing. Web-based resources have recently been developed to facilitate the identification of nucleotide changes that could alter splicing. However, computer predictions do not always correlate with in vivo splicing defects. The issue of unclassified variants in cancer predisposing genes is very important both for the correct ascertainment of cancer risk and for the understanding of the basic mechanisms of cancer gene function and regulation. Therefore we aimed to verify how predictions that can be drawn from in silico analysis correlate with results obtained in an in vivo splicing assay.
We analysed 99 hMLH1 and hMSH2 missense mutations with six different algorithms. Transfection of three different cell lines with 20 missense mutations, showed that a minority of them lead to defective splicing. Moreover, we observed that some exons and some mutations show cell-specific differences in the frequency of exon inclusion.
Our results suggest that the available algorithms, while potentially helpful in identifying splicing modulators especially when they are located in weakly defined exons, do not always correspond to an obvious modification of the splicing pattern. Thus caution must be used in assessing the pathogenicity of a missense or silent mutation with prediction programs. The variations observed in the splicing proficiency in three different cell lines suggest that nucleotide changes may dictate alternative splice site selection in a tissue-specific manner contributing to the widely observed phenotypic variability in inherited cancers.
BMC Genomics 02/2006; 7:243. · 4.07 Impact Factor
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ABSTRACT: Hereditary haemorrhagic telangiectasia (HHT or Rendu-Osler-Weber syndrome) is an autosomal dominant disorder characterized by localized angiodysplasia due to mutations in endoglin, ALK-1 gene, and a still unidentified locus. The lack of highly recurrent mutations, locus heterogeneity, and the presence of mutations in almost all coding exons of the two genes makes the screening for mutations time-consuming and costly. In the present study, we developed a DHPLC-based protocol for mutation detection in ALK1 and ENG genes through retrospective analysis of known sequence variants, 20 causative mutations and 11 polymorphisms, and a prospective analysis on 47 probands with unknown mutation. Overall DHPLC analysis identified the causative mutation in 61 out 66 DNA samples (92.4%). We found 31 different mutations in the ALK1 gene, of which 15 are novel, and 20, of which 12 are novel, in the ENG gene, thus providing for the first time the mutational spectrum in a cohort of Italian HHT patients. In addition, we characterized the splicing pattern of ALK1 gene in lymphoblastoid cells, both in normal controls and in two individuals carrying a mutation in the non-invariant –3 position of the acceptor splice site upstream exon 6 (c.626-3C>G). Functional essay demonstrated the existence, also in normal individuals, of a small proportion of ALK1 alternative splicing, due to exon 5 skipping, and the presence of further aberrant splicing isoforms in the individuals carrying the c.626-3C>G mutation. © 2006 Wiley-Liss, Inc.
Human Mutation 01/2006; 27(2):213 - 214. · 5.69 Impact Factor
