Adenine phosphoribosyltransferase (APRT) deficiency: identification of a novel nonsense mutation.

BACKGROUND: Adenine phosphoribosyltransferase deficiency (APRTD) is an under estimated genetic form of kidney stones and/or kidney failure, characterized by intratubular precipitation of 2,8-dihydroxyadenine crystals (2,8-DHA). Currently, five pathologic allelic variants have been identified as responsible of the complete inactivation of APRT protein. CASE PRESENTATION: In this study, we report a novel nonsense mutation of the APRT gene from a 47- year old Italian patient. The mutation, localized in the exon 5, leads to the replacement of a cytosine with a thymine (g.2098C > T), introducing a stop codon at amino acid position 147 (p.Gln147X).This early termination was deleterious for the enzyme structural and functional integrity, as demonstrated by the structure analysis and the activity assay of the mutant APRT protein. CONCLUSION: These data revealed that the p.Gln147X mutation in APRT gene might be a new cause of APRT disease.

High-sensitive cardiac troponin T (hs-cTnT) assay as serum biomarker to predict cardiac risk in myotonic dystrophy: A case-control study.

BACKGROUND: Myotonic dystrophy (DM) is a genetic disorder caused by nucleotide repeats expansion. Sudden death represents the main cause of mortality in DM patients. Here, we investigated the relationship between serum cardiac biomarkers with clinical parameters in DM patients. METHODS: Case-control study included 59 DM patients and 22 healthy controls. An additional group of 62 controls with similar cardiac defects to DM were enrolled. RESULTS: NT-proBNP, hs-cTnT and CK levels were significantly increased in DM patients compared to healthy subjects (p=0.0008, p<0.0001, p<0.0001). Also, hs-cTnT levels were significantly higher in DM compared to control group with cardiac defects (p=0.0003). Positive correlation was found between hs-cTnT and hs-cTnI in both DM patients and controls (p=0.019, p=0.002). Independently from the age, the risk of DM disease was positively related to an increase in hs-cTnT (p=0.03). On the contrary, the risk of DM was not related to hs-cTnI, but was evidenced a role of PR interval (p=0.03) and CK (p=0.08). CONCLUSIONS: The levels of hs-cTnT were significantly higher in DM patients. Analysis, with anti-cTnT, shows that this increase might be linked to heart problems. This last finding suggests that hs-cTnT might represent a helpful serum biomarker to "predict" cardiac risk in DM disease.

Development and Validation of a New Molecular Diagnostic Assay for Detection of Myotonic Dystrophy Type 2.

BACKGROUND: Myotonic dystrophy (DM) is the most common adult form of muscular dystrophy, characterized by autosomal dominant progressive myopathy, myotonia, and multiorgan involvement. Myotonic dystrophy type 2 (DM2) is caused by a [CCTG] expansion in the ZNF9/CNBP gene. The aim of this work was the validation of the new molecular diagnostic test Myotonic Dystrophy type 2 kit-FL. RESULTS: A cohort of 126 individuals was analyzed. The results show that 126/126 patients were correctly identified using the new molecular assay. In particular, 74 were DM2 positive, 39 were DM2/DM1 negative and 13 DM2 negative/DM1 positive. Approximately 9.5% (7/74) of the DM2-positive samples had a single sizeable expansion and 85% (63/74) showed multiple bands or smears. Comparative fluorescence in situ hybridization (FISH) analyses, on muscle biopsies, revealed that the sensitivity and specificity were very high (>99%). Equivalent analytical performances were obtained using different DNA extraction methods. Among affected individuals 87.5% (28/32) had electrical myotonia, 69% (22/32) proximal weakness, 41% (13/32) cataracts, and about 37.5% (12/32) cardiac conduction defects. FISH analysis and clinical data were used to support the genetic analysis.

Emergence of Carbapenem-Resistant Klebsiella pneumoniae: Progressive Spread and Four-Year Period of Observation in a Cardiac Surgery Division.

Frequent use of carbapenems has contributed to the increase to K. pneumoniae strains resistant to this class of antibiotics (CRKP), causing a problem in the clinical treatment of patients. This investigation reports the epidemiology, genetic diversity, and clinical implication of the resistance to drugs mediated by CRKP in our hospital. A total of 280 K. pneumoniae strains were collected; in particular 98/280 (35%) were CRKP. Sequencing analysis of CRKP isolated strains showed that 9/98 of MBL-producing strains carried the bla VIM-1 gene and 89/98 of the isolates were positive for bla KPC-2. Antimicrobial susceptibility tests revealed a complete resistance to third-generation cephalosporins and a moderate resistance to tigecycline, gentamicin, and fluoroquinolones with percentages of resistance of 61%, 64%, and 98%, respectively. A resistance of 31% was shown towards trimethoprim-sulfamethoxazole. Colistin was the most active agent against CRKP with 99% of susceptibility. Clonality was evaluated by PFGE and MLST: MLST showed the same clonal type, ST258, while PFGE analysis indicated the presence of a major clone, namely, pulsotype A. This finding indicates that the prevalent resistant isolates were genetically related, suggesting that the spread of these genes could be due to clonal dissemination as well as to genetic exchange between different clones.

Identification and characterization of DM1 patients by a new diagnostic certified assay: neuromuscular and cardiac assessments.

The expansion of the specific trinucleotide sequence, [CTG], is the molecular pathological mechanism responsible for the clinical manifestations of DM1. Many studies have described different molecular genetic techniques to detect DM1, but as yet there is no data on the analytical performances of techniques used so far in this disease. We therefore developed and validated a molecular method, "Myotonic Dystrophy SB kit," to better characterize our DM1 population. 113 patients were examined: 20 DM1-positive, 11 DM1/DM2-negative, and13 DM1-negative/DM2-positive, who had a previous molecular diagnosis, while 69 were new cases. This assay correctly identified 113/113 patients, and all were confirmed by different homemade assays. Comparative analysis revealed that the sensitivity and the specificity of the new kit were very high (>99%). Same results were obtained using several extraction procedures and different concentrations of DNA. The distribution of pathologic alleles showed a prevalence of the "classical" form, while of the 96 nonexpanded alleles 19 different allelic types were observed. Cardiac and neuromuscular parameters were used to clinically characterize our patients and support the new genetic analysis. Our findings suggest that this assay appears to be a very robust and reliable molecular test, showing high reproducibility and giving an unambiguous interpretation of results.