Rossella Tomaiuolo

Increased BDNF Promoter Methylation in the Wernicke Area of Suicide Subjects

CONTEXT Brain-derived neurotrophic factor (BDNF) plays a pivotal role in the pathophysiology of suicidal behavior and BDNF levels are decreased in the brain and plasma of suicide subjects. So far, the mechanisms leading to downregulation of BDNF expression are poorly understood. OBJECTIVES To test the hypothesis that alterations of DNA methylation could be involved in the dysregulation of BDNF gene expression in the brain of suicide subjects. DESIGN Three independent quantitative methylation techniques were performed on postmortem samples of brain tissue. BDNF messenger RNA levels were determined by quantitative real-time polymerase chain reaction. SETTING Academic medical center. PATIENTS OR OTHER PARTICIPANTS Forty-four suicide completers and 33 nonsuicide control subjects of white ethnicity. MAIN OUTCOME MEASURES The DNA methylation degree at BDNF promoter IV and the genome-wide DNA methylation levels in the brains Wernicke area. RESULTS Postmortem brain samples from suicide subjects showed a statistically significant increase of DNA methylation at specific CpG sites in BDNF promoter/exon IV compared with nonsuicide control subjects (P < .001). Most of the CpG sites lying in the -300/+500 region, on both strands, had low or no methylation, with the exception of a few sites located near the transcriptional start site that had differential methylation, while genome-wide methylation levels were comparable among the subjects. The mean methylation degree at the 4 CpG sites analyzed by pyrosequencing was always less than 12.9% in the 33 nonsuicide control subjects, while in 13 of 44 suicide victims (30%), the mean methylation degree ranged between 13.1% and 34.2%. Higher methylation degree corresponded to lower BDNF messenger RNA levels. CONCLUSIONS BDNF promoter/exon IV is frequently hypermethylated in the Wernicke area of the postmortem brain of suicide subjects irrespective of genome-wide methylation levels, indicating that a gene-specific increase in DNA methylation could cause or contribute to the downregulation of BDNF expression in suicide subjects. The reported data reveal a novel link between epigenetic alteration in the brain and suicidal behavior.

Congenital diarrheal disorders: Improved understanding of gene defects is leading to advances in intestinal physiology and clinical management

Congenital diarrheal disorders (CDD, Online Mendelian Inheritance in Man [OMIM] 251850) represent one of the most challenging clinical conditions for pediatric gastroenterologists because of the severity of the clinical picture and the broad range of disorders in its differential diagnosis. The number of conditions included within CDD has gradually increased. Recent advances made in the pathophysiology of these conditions have led to a better understanding of the more common diarrheal diseases. Based on the body of data accumulated in recent years, we suggest that CDD be classified in 4 categories depending on the alteration in absorption and transport of nutrients and electrolytes, enterocyte differentiation and polarization, enteroendocrine cell differentiation, and modulation of the intestinal immune response. Our knowledge of the genes responsible for CDD is also rapidly increasing, thanks to linkage studies based on genome-wide analysis of polymorphisms. In this context, the identification of disease genes is a step forward in the diagnostic approach to a patient in whom CDD is strongly suspected. However, it is conceivable that faster, less expensive molecular procedures will, in the near future, become available. This approach could spare the patient invasive procedures and limit complications associated with a delay in diagnosis. Furthermore, carrier and prenatal molecular diagnosis may help pediatricians better manage the condition in the early stages of life.

Lung cancer metastatic cells detected in blood by reverse transcriptase-polymerase chain reaction and dot-blot analysis.

PURPOSE We analyzed the blood of patients with lung cancer at different stages of presentation for the presence of carcinoembryonic antigen (CEA) mRNA detected by reverse transcriptase-polymerase chain reaction (RT-PCR) combined with the dot-blot procedure as an indicator of micrometastatic malignant cells. PATIENTS AND METHODS We studied 24 lung cancer patients (10 with distant metastases and 14 with no evidence of distant metastases), eight age- and sex-matched patients affected by nonneoplastic respiratory diseases (four smokers), and eight healthy subjects. We used immunohistochemistry and RT-PCR dot-blot analysis to evaluate CEA expression in the neoplastic tissue, and the RT-PCR dot-blot procedure to analyze CEA mRNA in circulating cells. RESULTS The RT-PCR dot-blot procedure was highly sensitive aspecific: it detected CEA mRNA in samples of RNA from lung cancer diluted 10(6)-fold with RNA extracted from normal blood cells, and sequence analysis confirmed that the amplified product was CEA. CEA mRNA was found in circulating cells from eight of 10 lung cancer patients with distant metastases (diagnostic sensitivity, 80%) and in four of 14 patients with no evidence of distant metastases. Two of the latter had distant metastases within 6 months of analysis. Thus, the diagnostic specificity of the analysis toward lung cancer without distant metastases was 86%. The analysis was negative in the eight nonneoplastic patients and in the eight healthy controls. CONCLUSION The RT-PCR dot-blot analysis of CEA mRNA in blood cells seems to be a promising tool for the early detection of micrometastatic circulating cells in patients with lung cancer.

Gene Mutation in MicroRNA Target Sites of CFTR Gene: A Novel Pathogenetic Mechanism in Cystic Fibrosis?

Cystic fibrosis (CF) is the most frequent lethal genetic disorder among Caucasians. It depends on alterations of a chloride channel expressed by most epithelial cells and encoded by CFTR gene. Also using scanning techniques to analyze the whole coding regions of CFTR gene, mutations are not identified in up to 10% of CF alleles, and such figure increases in CFTR-related disorders (CFTR-RD). Other gene regions may be the site of causing-disease mutations. We searched for genetic variants in the 1500 bp of CFTR 3′ untranslated region, typical target of microRNA (miRNA) posttranscriptional gene regulation, in either CF patients with the F508del homozygous genotype and different clinical expression (n = 20), CF (n = 32) and CFTR-RD (n = 43) patients with one or none mutation after CFTR scanning and in controls (n = 50). We identified three SNPs, one of which, the c.*1043A>C, was located in a region predicted to bind miR-433 and miR-509-3p. Such mutation was peculiar of a CFTR-RD patient that had Congenital Bilateral Absence of Vas Deferens (CBAVD), diffuse bronchiectasis, a borderline sweat chloride test and the heterozygous severe F508del mutation on the other allele. The expression analysis demonstrated that the c.*1043A>C increases the affinity for miR-509-3p and slightly decreases that for the miR-433. Both miRNAs cause in vitro a reduced expression of CFTR protein. Thus, the c.*1043A>C may act as a mild CFTR mutation enhancing the affinity for inhibitory miRNAs as a novel pathogenetic mechanism in CF.

Molecular diagnosis of cystic fibrosis: comparison of four analytical procedures.

Abstract We compared the analytical accuracy, times, costs and the detection rate of four procedures for the molecular analysis of cystic fibrosis (CF). DNA from 127 subjects bearing different genotypes was tested by denaturating gradient gel electrophoresis followed by sequencing (reference procedure) and, for comparison, by ASO dot-blot (in-house), reverse dot-blot (Innogenetics), ARMS (Zeneca Diagnostics) and OLA-PCR (PE Applied Biosystem). To assess inter-observer variability, all samples were tested twice. To evaluate intra- and between-series variability, two samples were tested twice in each series. All the procedures yielded reproducible results and assigned the correct genotype to each sample. ASO dot-blot is the cheapest procedure but has the longest analytical time (>24 h) and uses radioactive labeling. It can be adapted to analyze peculiar mutations in specific ethnic groups. ARMS from Zeneca Diagnostics is rapid (4 h), easy to perform, but, except for the ∆F508 mutation, does not distinguish the homozygote from the heterozygote genotype. It could be used for carrier analysis in families with known mutations. OLA-PCR has the highest detection rate in most ethnic groups, is automated for capillary electrophoresis but requires a high level of operator expertise: it is suitable when collected series of samples are analyzed from large patient cohorts. Reverse dot-blot is easy to perform and can be semiautomated: it can be used as first-line screening test. Given the heterogeneity of CF mutations, commercial kits should be developed to analyze mutations peculiar to specific ethnic groups.

Comprehensive Cystic Fibrosis Mutation Epidemiology and Haplotype Characterization in a Southern Italian Population

We screened the whole coding region of the cystic fibrosis transmembrane regulator (CFTR) gene in 371 unrelated cystic fibrosis (CF) patients from three regions of southern Italy. Forty‐three mutations detected 91.5% of CF mutated chromosomes by denaturing gradient gel electrophoresis analysis, and three intragenic CFTR polymorphisms predicted a myriad of rare mutations in uncharacterized CF chromosomes. Twelve mutations are peculiar to CF chromosomes from southern Italy: R1158X, 4016insT, L1065P and 711+1G>T are present in 6.3% of CF chromosomes in Campania; G1244E and 852del22 are present in 9.6% of CF chromosomes in Basilicata and 4382delA, 1259insA, I502T, 852del22, 4016insT, D579G, R1158X, L1077P and G1349D are frequent in Puglia (19.6% of CF alleles). Several mutations frequently found in northern Italy (e.g., R1162X, 711+5G>T) and northern Europe (e.g., G551D, I507del and 621+1G>T) are absent from the studied population. The I148T‐3195del6 complex allele was present in two CF chromosomes, whereas I148T was present in both alleles (as a single mutation) in another CF patient and in five CF carriers; this could result from crossover events. The haplotype analysis of three intragenic polymorphisms (IVS8CA, IVS17bTA and IVS17bCA) compared with data from other studies revealed that several mutations (3849+10kbC>T, 1717‐1G>A, E585X, 3272‐26G>A, L558S, 2184insA and R347P) originated from multiple events, whereas others (R1158X and S549R) could be associated with one or more intragenic recombinant events. Given the large population migration from southern Italy, knowledge of the CF molecular epidemiology in this area is an important contribution to diagnosis, counselling and interlaboratory quality control for molecular laboratories worldwide.

Extensive Molecular Analysis of Patients Bearing CFTR-Related Disorders

Cystic fibrosis transmembrane conductance regulator (CFTR)-related disorders (CFTR-RDs) may present with pancreatic sufficiency, normal sweat test results, and better outcome. The detection rate of mutations is lower in CFTR-RD than in classic CF: mutations may be located in genes encoding proteins that interact with CFTR or support channel activity. We tested the whole CFTR coding regions in 99 CFTR-RD patients, looking for gene mutations in solute carrier (SLC) 26A and in epithelial Na channel (ENaC) in 33 patients who had unidentified mutations. CFTR analysis revealed 28 mutations, some of which are rare. Of these mutations, RT-PCR demonstrated that the novel 1525-1delG impairs exon 10 splicing; by using minigene analysis, we excluded the splicing effect of three other novel intronic variants. Analysis of SLC26A genes revealed several variants, some of which are novel, that did not affect mRNA expression. Other mutations occurred in the ENaC genes encoding the ENaC subunits, but their frequency did not significantly differ between patients and controls. Our data, although obtained on a preliminary cohort of CFTR-RD patients, exclude a role of mutations in SLC26A and in SCNN genes in the pathogenesis of such disease; we confirm that CFTR analysis has a relevant role in CFTR-RD patients; and it appears mandatory to use CFTR scanning techniques and approaches to reveal the effect of novel mutations.

TrkB gene expression and DNA methylation state in Wernicke area does not associate with suicidal behavior

BACKGROUND Alterations of DNA methylation and expression of suicide-related genes occurring in specific brains areas have been associated to suicidal behavior. In the BDNF pathway, TrkB gene in frontal cortex and hippocampus, and BDNF gene in Wernicke area have been found hypermethylated and down-regulated in suicide subjects as compared to controls. In this work we investigated whether epigenetic modifications of TrkB gene occur in Wernicke area of 18 suicide subjects as compared to 18 controls. METHODS MassArray analysis was performed to determine the methylation degree of TrkB promoter in post-mortem samples. TrkB full length and TrkB-T1 mRNA levels were assessed by quantitative RT-PCR. Geometric averaging of four internal control genes was calculated for normalization of results. RESULTS We found that TrkB and TrkB-T1 expression and promoter methylation in Wernicke area did not correlate with suicidal behavior whereas, in the same samples, the BDNF promoter IV was significantly hypermethylated in suicide with respect of controls. LIMITATION Data from a single brains area in this studys sample. CONCLUSIONS Our data show that no correlation exists between TrkB gene methylation and suicide in Wernicke area, confirming that expression and methylation state of suicide-related genes, even belonging to the same pathway, may be specific for brain area.

Epidemiology and a novel procedure for large scale analysis of CFTR rearrangements in classic and atypical CF patients: A multicentric Italian study

BACKGROUND Mutation epidemiology in each ethnic group is a crucial step of strategies for cystic fibrosis (CF) diagnosis and counselling. To date, the scanning of the whole coding region of the cystic fibrosis transmembrane conductance regulator (CFTR) gene permits to identify about 90% of alleles from patients bearing CF and a lower percentage in patients bearing atypical CF. CFTR rearrangements in heterozygosis elude current techniques for molecular analysis, and some of them have been reported with a frequency up to 6% in various ethnic groups. METHODS Using quantitative PCR analysis of all coding regions, we assessed the occurrence of CFTR rearrangements in 130 alleles from classic CF patients and in 198 alleles from atypical CF patients (all unrelated and from Italian descent) bearing unidentified mutations after the scanning of CFTR. RESULTS Seven rearrangements (i.e., dele1, dele2, dele2_3, dele 14b_17b, dele17a_18, dele22_23, and dele22_24) were identified in 34/131 (26.0%) CF alleles bearing undetected mutations (which means about 2.5% of all CF alleles) and in none of the 198 alleles from atypical CF. The CFTR haplotype and the sequence analysis of the breakpoints confirmed the common origin of all the rearrangements. Thus, we set up a novel duplex PCR assay for the large-scale analysis of the seven rearrangements. The procedure was rapid (all PCR amplifications were obtained under the same conditions), costless and repeatable. CONCLUSIONS It is useful to select the CFTR rearrangements more frequent in specific ethnic groups and to set up procedures for large-scale analysis. Their study can be performed in cases in which a high detection rate is required (i.e., partners of CF carriers/patients). On the contrary, the analysis of rearrangement is useless in atypical CF patients.

Congenital Diarrheal Disorders: An Updated Diagnostic Approach

Congenital diarrheal disorders (CDDs) are a group of inherited enteropathies with a typical onset early in the life. Infants with these disorders have frequently chronic diarrhea of sufficient severity to require parenteral nutrition. For most CDDs the disease-gene is known and molecular analysis may contribute to an unequivocal diagnosis. We review CDDs on the basis of the genetic defect, focusing on the significant contribution of molecular analysis in the complex, multistep diagnostic work-up.