Diana Valverde Pérez

Estudio de la repetición del pentanucleótido CCTTT en el gen de la sintasa inducible del óxido nítrico en pacientes con hipertensión arterial pulmonar

INTRODUCTION One of the pathways involved in pulmonary arterial hypertension (PAH) is the nitric oxide (NO) pathway. A polymorphism in the inducible NO synthase (NOS2) gene has been described, consisting of the CCTTT pentanucleotide repeat, which causes a reduction in NO production. The aim of this study was to determine if this polymorphism increases susceptibility to developing PAH. METHODS Sixty four patients with a diagnosis of PAH groupsi and iv and 50 healthy controls were compared. DNA genotyping of the samples for this polymorphism was performed using PCR. The distribution between both groups was compared and correlated with clinical and haemodynamic parameters and therapeutic response. RESULTS A significantly different distribution was observed in the number of repeats between patients and controls (P<.0001). When the samples were categorised by short forms (both alleles with less than 12repeats) and long forms (≥12 repeats), it was observed that the former had an almost 4-fold risk of developing PAH (odds ratio: 3.83; 95%CI: 1.19-12.32, P=.024). There were no differences between the most common types of PAH, either in therapeutic response or survival. There was no correlation between haemodynamic parameters and the number of repeats in the patients, and only a weak correlation with systolic PAH. CONCLUSIONS There are significant differences in the distribution of the NOS2 promotor CCTTT polymorphism between patients with PAH and the healthy population. A minor CCTTT pentanucleotide repeat in the NOS2 gene may increase the risk of developing PAH.

Viabilidad de las muestras ganglionares obtenidas por ecobroncoscopia para el estudio de alteraciones epigenéticas en pacientes con cáncer de pulmón

INTRODUCTION The diagnosis of microscopic lymph node metastasis in lung cancer is challenging despite the constant advances in tumor staging. The analysis of the methylation status of certain genes in lymph node samples could improve the diagnostic capability of conventional cyto-histological methods. The aim of this study was to demonstrate the feasibility of methylation studies using cytological lymph node samples. METHODS Prospective study including 88 patients with a diagnosis or strong suspicion of non-small cell lung cancer, in which an echobronchoscopy was performed on mediastinal or hilar lymph nodes for diagnostic and/or staging. DNA was extracted from cytological lymph node samples and sodium bisulfite modification was performed. Methylation studies for p16/INK4a and SHOX2 were accomplished by MS-qPCR and pyrosequencing. RESULTS The methodology used in our study yielded optimal/good DNA quality in 90% of the cases. No differences in DNA concentration were observed with respect to the lymph node biopsied and final diagnosis. Methylation analyses using MS-qPCR and pyrosequencing were not possible in a small number of samples mainly due to low DNA concentration, inadequate purity, fragmentation and/or degradation as a consequence of bisulfite conversion. CONCLUSION Methylation quantification using MS-qPCR and pyrosequencing of cytological lymph node samples obtained using echobronchoscopy is feasible if an appropriate DNA concentration is obtained, notably contributing to the identification of epigenetic biomarkers capable of improving decision-making for the benefit of potentially curable lung cancer patients.

Estudio clínico y molecular de 4 casos de hipertensión pulmonar asociada a sarcoidosis

Sarcoidosis is a pleomorphic disease that can present with pulmonary hypertension (PH). What little information is available about the association of these two diseases comes mainly from small series of patients scheduled for transplant. We present 4 cases of mild pulmonary involvement in whom right catheterisation was performed and PH-specific therapy was administered. After obtaining written consent, a genetic study was performed that showed mutations in PH-related genes in 3 of the patients. This is the first study of its kind to yield genetic information for this type of PH.

Glutathione S-transferase M1 and T1 null genotypes increase susceptibility to drug-induced liver injury.

We read with interest the work of Lucena et al. about genetic susceptibility to drug-induced liver injury (DILI).1 There is an interest in studying the possible relationship between glutathione S-transferase (GST) at the M1 and T1 loci and the risk of hepatotoxicity secondary to drugs. The study of these genetic polymorphisms should be considered a target in the investigation of drugrelated hepatotoxicity mediated by metabolic idiosyncratic mechanisms.2-4 However, in many cases, the drug-metabolism pathways and the exact mechanism and factors contributing to liver toxicity remain poorly understood. From pharmacological studies, there are data showing that GST genotypes may be linked to DILI secondary to hepatocellular damage mechanisms based on the participation of GST enzymes in drug metabolism.4 Thus, studying drugs in which the DILI mechanism is unknown or secondary to a hypersensitive reaction could be confusing. Most of these investigations have been performed in Asian patients exposed to antituberculosis drugs; it is known that GST enzymes play an important role in isoniazid metabolism.5-7 Lucena et al. included patients with DILI in whom the main causative therapeutic group of drugs were anti-infectives, especially amoxicillin-clavulanic acid. Among the group who received anti-infective drugs, only five patients were receiving antituberculosis drugs, which were not specified by the authors. Among these five patients, four showed one of these null polymorphisms (GSTM1 or GSTT1) and one had a normal genotype, but the authors did not specify the combination of the null alleles or in which genes. The absence of this data is general for all types of drugs studied; there is no information about what gene was predominantly deleted for each drug. Again, focusing on the antituberculosis drug group, it is not surprising there was no association between the presence of GSTM1 and GSTT1-null mutations and the risk of DILI due to the small number of patients in this subgroup. Our group performed the first study with 95 Caucasian patients originally from Spain to investigate the influence of these null polymorphisms on the risk of antituberculosis drug-induced hepatotoxicity and showed an enhanced risk of DILI in GSTT1-null carriers (odds ratio 2.6; P 0.03).8 The frequency of double GSTM1 and GSTT1 genotype carriers was higher in cases than in controls; however, these differences did not reach significance because the power of the associations related to the small size of the patient subgroup. The study by Lucena et al. corroborated this observation.1 We also observed a possible association between the risk of severe hepatotoxicity and the presence of the GSTT1-null polymorphism among six patients with severe hepatotoxicity; five (83.3%) presented with the GSTT1-null polymorphism (P 0.08). Moreover, the maximum peak of alanine aminotransferase was higher among patients with the GSTT1-null polymorphism {342 IU/L [Interquartile Range (IQR) 167-755] versus 216 IU/L [IQR 150-271]}, although without significance (P 0.07; unpublished data). A concern about the methodology used must be considered. Although there were no differences in the frequency of the null mutations between the healthy control group and the drug-control group, we think that the use of a nonmatched drug-control group for comparison in the final analysis could be an important limitation because they are not exposed to the drug that can potentially produce DILI. Despite these considerations, published data support a possible role in the enhanced susceptibility of GST polymorphism carriers for DILI, so we agree with the authors that future studies are needed to evaluate the relevance of these polymorphisms on the risk of DILI in each drug group and population in order to evaluate its possible application in the prevention of this adverse effect.