VARS2 and TARS2 mutations in patients with mitochondrial encephalomyopathies.

By way of whole-exome sequencing, we identified a homozygous missense mutation in VARS2 in one subject with microcephaly and epilepsy associated with isolated deficiency of the mitochondrial respiratory chain (MRC) complex I and compound heterozygous mutations in TARS2 in two siblings presenting with axial hypotonia and severe psychomotor delay associated with multiple MRC defects. The nucleotide variants segregated within the families, were absent in Single Nucleotide Polymorphism (SNP) databases and are predicted to be deleterious. The amount of VARS2 and TARS2 proteins and valyl-tRNA and threonyl-tRNA levels were decreased in samples of afflicted patients according to the genetic defect. Expression of the corresponding wild-type transcripts in immortalized mutant fibroblasts rescued the biochemical impairment of mitochondrial respiration and yeast modeling of the VARS2 mutation confirmed its pathogenic role. Taken together, these data demonstrate the role of the identified mutations for these mitochondriopathies. Our study reports the first mutations in the VARS2 and TARS2 genes, which encode two mitochondrial aminoacyl-tRNA synthetases, as causes of clinically distinct, early-onset mitochondrial encephalopathies.

Human chitotriosidase: a sensitive biomarker of sarcoidosis.

BACKGROUND: Sarcoidosis is a multisystem granulomatous disease of unknown etiology. No suitable biomarkers are available to evaluate the evolution of this disease, which still has an unpredictable clinical course. Some years ago our research group proposed chitotriosidase as a potential biomarker with prognostic value, that however needed to be validated. AIMS AND METHODS: The aims of this study were to evaluate the sensitivity and specificity of chitotriosidase in a population of 232 sarcoidosis patients under the observation of our Sarcoidosis Regional Referral Centre in Siena and to analyse enzyme concentrations in different disease phenotypes (as defined by the recently published COS classification) to define its prognostic value. RESULTS: Serum chitotriosidase concentrations were significantly higher in patients than in healthy controls (p<0.0001) and were directly correlated with ACE levels (r=0.25, p<0.0001). ROC curve analysis revealed 88.6 % sensitivity and 92.8 % specificity. Enzyme concentrations were significantly higher in stage 3 sarcoidosis than in stage 0 (p=0.02). The lowest concentrations of chitotriosidase were found in untreated patients in remission (COS-1), while the highest enzyme concentrations were found in symptomatic patients with persistent disease on steroids and with functional deterioration in the last year (COS-9). In COS-9 subgroup, chitotriosidase decreased significantly after the increasing of steroid dose or the introduction of a new immunosuppressant therapy (p<0.01). CONCLUSION: Chitotriosidase proved to be a biomarker with good sensitivity and specificity that is easily detected in serum. It can be proposed in clinical practice to identify progressive patients requiring close follow-up, to detect relapses and to evaluate the effects of therapy.

HLA-DQ typing in the diagnostic algorithm of celiac disease.

OBJECTIVE: celiac disease (CD) is an immune-mediated chronic inflammatory disease associated with HLA-DQ2 and DQ8 molecules. We evaluated the role of HLA in the CD diagnostic algorithm in order to contribute to the development of practical indications for the use of HLA typing. MATERIAL AND METHODS: we selected 317 subjects typed for DR-DQ genes. CD was present in 123 patients, and 89 were included in the study; a control sample of 70 healthy individuals was recruited. RESULTS: 64% of patients with CD carried DQ2 heterodimer (α5ß2), 13.5% carried DQ8 heterodimer without DQ2, 21.4% only showed ß2 chain and 1.1% were positive for DQ2 α5 chain. The only presence of α5 chain did not predispose to CD, while DQB1*02 allele resulted more frequent than in other reports, pointing out the intrinsic correlation between ß2 chain and CD. In the case-control study we observed a progression of increased risk, ranging from 1:7 for HLA-DQ2 homozygous to 1:85 for DQ8 heterozygous subjects. Overall, 8,6% of first degree family members were affected, exclusively in presence of HLA-DQ2, -DQ8 or DQB1*02, and CD was significantly more frequent among siblings than parents. Finally, considering the different patterns of clinical presentation among the HLA-DQ risk classes identified we found no relationship between CD clinical presentation and HLA-DQ risk categories. CONCLUSIONS: our results strengthen the evidence that HLA-DQ status strongly influences the development of CD and demonstrate that knowledge of a patient's HLA-DQ genotype allows to establish clinically relevant genetic risk profiles.

A second MNGIE patient without typical mitochondrial skeletal muscle involvement.

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an autosomal recessive disease caused by mutations in the gene encoding thymidine phosphorylase (TYMP). Clinically, MNGIE is characterized by gastrointestinal dysmotility, cachexia, ptosis, ophthalmoparesis, peripheral neuropathy and leukoencephalopathy. Most MNGIE patients have signs of mitochondrial dysfunction in skeletal muscle at morphological and enzyme level, as well as mitochondrial DNA depletion, multiple deletions and point mutations. A case without mitochondrial skeletal muscle involvement and with a TYMP splice-acceptor site mutation (c. 215-1 G>C) has been reported. Here, we describe an Italian patient with the same mutation and without mitochondrial skeletal muscle involvement, suggesting a possible genotype-phenotype correlation.

Late-onset MNGIE without peripheral neuropathy due to incomplete loss of thymidine phosphorylase activity.

Mitochondrial NeuroGastroIntestinal Encephalomyopathy (MNGIE) is an autosomal recessive disorder characterized by severe gastrointestinal dysmotility, cachexia, peripheral neuropathy, ptosis, ophthalmoplegia, and leukoencephalopathy with early onset and severe prognosis. Mutations in the TYMP/ECGF1 gene cause a loss of thymidine phosphorylase catalytic activity, disrupting the homeostasis of intramitochondrial nucleotide pool. We report a woman with a very late onset of MNGIE, lacking peripheral neuropathy. Thymidine phosphorylase activity was markedly reduced in cultured fibroblasts, but only mildly reduced in buffy coat, where the defect is usually detected, and plasma thymidine was mildly increased compared to typical MNGIE patients. TYMP/ECGF1 analysis detected two heterozygous mutations, including a novel missense mutation. These findings indicate that a partial loss of thymidine phosphorylase activity may induce a late-onset and incomplete MNGIE phenotype.

Spermatogenesis in a man with complete deletion of USP9Y.

Deletions in the azoospermia factor region AZFa on the human Y chromosome and, more specifically, in the region that encompasses the ubiquitin-specific peptidase 9, Y-linked gene USP9Y have been implicated in infertility associated with oligospermia and azoospermia. We have characterized in detail a deletion in AZFa that results in an absence of USP9Y in a normospermic man and his brother and father. The association of this large deletion with normal fertility shows that USP9Y, hitherto considered a candidate gene for infertility and azoospermia, does not have a key role in male reproduction. These results suggest that it may not be necessary to consider USP9Y when screening the Y chromosome of infertile or subfertile men for microdeletions.

Postictal serum nucleotidases activities in patients with epilepsy.

Adenosine, a potent anticonvulsant, can be produced in the body by the hydrolysis of adenine nucleotides through the action of ecto- or soluble nucleotidases. Changes in nucleotide hydrolysis occur after pentylenetetrazol-induced epileptic events. We evaluated serum ATP, ADP and AMP hydrolysis rates and soluble nucleotide phosphodiesterase (PDEase) activity at 5, 10, 15, 30 and 60 min, and 12h following an epileptic event. Fifteen patients (seven female, eight male; mean age 15.5 years) were included in the study. The type of seizure was generalized in four patients and was localization related in the remaining 11. There were no differences in adenine nucleotide hydrolysis rates between patients and healthy subjects in the interictal stage. In comparison with controls, ATP, ADP and AMP hydrolysis rates were significantly increased at 5 min (53+/-1.4%, 79.2+/-2.8% and 37.0+/-2.6%, respectively) and up to 30 min following the epileptic event. In contrast to ADP and AMP, ATP hydrolysis remained significantly increased at 60 min (71.4+/-1.6%), returning to the basal level after 12h. Serum PDEase activity was also significantly higher in the patients than in healthy subjects, peaking at 15 min (61+/-2.9%) and remaining significantly increased up to 60 min (4.6+/-1.2%) following the epileptic episode. Globally, the variations in the postictal serum ADP hydrolysis rate almost overlapped those of AMP hydrolysis, whereas changes in the ATP hydrolysis rate overlapped those of PDEase activity. The clinical significance of this elevation in postictal soluble serum nucleotidase activity remains to be clarified. However, it is possible to hypothesize that the higher nucleotidase activity might play a role in the modulation of epileptic events.

Chitotriosidase and soluble IL-2 receptor: comparison of two markers of sarcoidosis severity.

BACKGROUND: Sarcoidosis is a multisystemic granulomatous disease with an unpredictable clinical course characterized by accumulation of activated proliferating T lymphocytes and mononuclear phagocytes in affected organs. AIMS AND METHODS: The aims of this study were to describe the clinical, radiological and immunological features of a population of sarcoidosis patients followed at the Sarcoidosis Regional Centre in Siena and to analyse chitotriosidase and sIL-2R concentrations in serum of these patients in order to understand their potential as disease markers. RESULTS: Chitotriosidase and sIL-2R concentrations in serum of sarcoidosis patients were found to be significantly higher than in healthy controls (p<0.01) and a positive correlation between the two markers was documented for the first time. Moreover, chitotriosidase and sIL-2R were expressed differently in different radiographic stages of the disease. CONCLUSION: Chitotriosidase and sIL-2R are two markers of sarcoidosis of different origin, the values of which show a correlation in these patients; they are easily detectable in serum and could be useful clinical markers of progression.

Chitotriosidase analysis in bronchoalveolar lavage of patients with sarcoidosis.

BACKGROUND: Sarcoidosis is a systemic granulomatous disease characterised by T-helper cell/macrophage alveolitis. Activated macrophages release mediators, such as cytokines, chemokines, oxygen radicals, and enzymes. In a previous paper we found higher levels of chitotriosidase, a macrophage derived enzyme, in serum of patients with sarcoidosis than in controls. Serum chitotriosidase levels were correlated with sarcoidosis radiological stages. Human chitotriosidase is involved in the pathogenesis of many lysosomal storage disorders and is selectively expressed in chronically activated tissue macrophages. METHODS: In the present study we determined chitotriosidase concentrations in bronchoalveolar lavage of patients with newly diagnosed pulmonary sarcoidosis (divided into two groups according to clinical parameters) and of controls with an ELISA test. RESULTS: Significantly different chitotriosidase concentrations were found in BAL of patients than controls, especially in patients with progressing disease. CONCLUSION: Chitotriosidase but not angiotensin converting enzyme concentrations correlated with sarcoidosis radiological stages, and also with the degree of lung infiltrate seen by CT-scan, suggesting that the former enzyme (detected locally and sistemically) may play a role in the pathogenesis of the disease. Further studies with a greater number of patients are needed to confirm this hypothesis and to determine whether chitotriosidase may be a marker of the severity of sarcoidosis.

Chitotriosidase activity in patients with interstitial lung diseases.

BACKGROUND: In previous papers, we found significantly higher activity of chitotriosidase, a macrophage derived enzyme, in serum and BAL of patients with sarcoidosis, especially in those with progressing disease and lung involvement, than in controls. Locally and systemically produced chitotriosidase activity was correlated with radiological stage and also with degree of lung infiltration, suggesting that this enzyme may play a role in the pathogenesis of sarcoidosis and may be used as a marker of disease severity. AIM: To analyse chitotriosidase activity in serum and bronchoalveolar lavage of patients with idiopathic pulmonary fibrosis and pulmonary fibrosis associated with systemic sclerosis and to compare it with chitotriosidase activity in controls and sarcoidosis patients. METHODS: Chitotriosidase activity was determined by a fluorometric assay. RESULTS: The results showed that serum chitotriosidase activity was only elevated in sarcoidosis patients; in patients with idiopathic pulmonary fibrosis and pulmonary fibrosis associated with systemic sclerosis it was in the normal range. On the contrary, in BAL of sarcoidosis and idiopathic pulmonary fibrosis patients the activity was significantly higher than in controls. CONCLUSION: Serum chitotriosidase is a potential marker of sarcoidosis severity; it increases in sarcoidosis in relation to radiological stage and degree of lung infiltration. The increase in chitotriosidase activity in BAL of sarcoidosis and idiopathic pulmonary fibrosis patients suggests that the enzyme could be involved in fibrogenesis in diffuse lung diseases. Further research is needed to understand the role of chitotriosidase in the pathogenesis of sarcoidosis and its involvement in fibrotic remodelling in certain diffuse lung diseases.

Chitotriosidase activity in the serum of patients with sarcoidosis and pulmonary tuberculosis.

BACKGROUND: Human chitotriosidase is a chitinase selectively expressed by activated macrophages. An increase in chitotriosidase activity was previously described by us in the serum and bronchoalveolar lavage of sarcoidosis patients. OBJECTIVE: The aim of the present study was to analyze serum chitotriosidase activity in a larger number of sarcoidosis patients to verify the reported increase with respect to controls and to compare serum chitotriosidase levels in patients with sarcoidosis and tuberculosis, two granulomatous disorders of different etiology. METHODS: Chitotriosidase activity was measured in the serum of 96 sarcoidosis patients, 15 pulmonary tuberculosis patients and 30 healthy controls. RESULTS: We found significantly higher serum chitotriosidase activity in sarcoidosis patients than controls (p < 0.01) and in sarcoidosis patients than tuberculosis patients (p < 0.01), confirming a striking elevation of chitotriosidase activity (>10 times greater than normal) in pulmonary sarcoidosis patients. This is the first time that chitotriosidase activity has been analyzed in the serum of patients with pulmonary tuberculosis; it was found to be significantly lower than in sarcoidosis patients and not significantly greater than in controls. CONCLUSION: Although the mechanisms leading to the increase in chitotriosidase activity in sarcoidosis are still unknown, this enzyme may be specifically involved in the pathogenesis of the disease. Further studies with a greater number of patients are needed to confirm these results and to determine whether chitotriosidase could be a marker with diagnostic or prognostic value in sarcoidosis.

Global developmental delay, osteopenia and ectodermal defect: a new syndrome.

UNLABELLED: Global developmental delay is a serious social problem. It is often unrecognized and the phenotypes are inadequately studied. To investigate the phenotypes of children with aspecific central nervous system (CNS) impairment (poor speech, maladaptive behavioral symptoms such as temper tantrums, aggressiveness, poor concentration and attention, impulsiveness, and mental retardation). SETTING: Tertiary care hospital. PATIENTS: Three children (two male siblings, and one unrelated girl). METHODS: We used the results from clinical neurological evaluations; imaging and electrodiagnostic studies; metabolic and genetic tests; skin biopsies and bone mineral densitometry. All three children suffered from (A) global developmental delay, (B) osteopenia, and (C) identical skin defects. The skin ultrastructural abnormalities were abnormal keratin differentiation, consisting of hyperkeratosis and granular layer thickening; sweat gland abnormalities, consisting of focal, cytoplasmic clear changes in eccrine secretory cells; and melanocyte abnormalities, with both morphological changes (reduced number and size without evident dendritic processes), and functional changes (defects in the migration of melanosomes in the keratinocytes). These patients present a previously unrecognized syndrome. We retain useful to report this new association, to be recognized, in the next future, as a specific key-sign of a well-defined genetic defect.

GM2 gangliosidosis variant B1 neuroradiological findings.

Variant B1 is a rare type of GM2 gangliosidosis. Clinically, it shows a wide spectrum of forms ranging from infantile to juvenile. We report the first magnetic resonance imaging (MRI) findings from three patients affected by GM2 gangliosidosis variant B1, two presenting with the infantile form and one with the juvenile form. The MRI appearances of the two patients with the infantile form disease are congruent with those reported for the early-onset type of both Tay-Sachs and Sandhoff diseases, and are characterized by early involvement of the basal ganglia and thalamus with cortical atrophy appearing later. In contrast, the patient with the juvenile form of variant B1 showed progressive cortical and white-matter atrophy of the supratentorial structures and, to a lesser extent, the infratentorial structures. No basal ganglia or thalamic anomalies were observed. Because in the adult forms of both Tay-Sachs and Sandhoff diseases a progressive cerebellar atrophy represents the only abnormality detectable, it appears that an MRI pattern peculiar to GM2 gangliosidosis can be defined. This pattern ranges from the basal ganglia injury associated with the early and severe demyelination process noted in the infantile form of the disease, to cerebellar atrophy with no supratentorial anomalies in the adult form. An "intermediate" MRI picture, with cortical atrophy and mild cerebellar atrophy, but without basal ganglia impairment, can be observed in the juvenile form. In addition, our investigations suggest that MRI abnormalities in GM2 gangliosidosis correlate with the clinical form of the disease rather than with the biochemical variant of the enzymatic defect.

Pathogenic mechanism, prophylaxis, and therapy of symptomatic acidosis induced by acetazolamide.

BACKGROUND: Acetazolamide, a noncompetitive carbonic anhydrase inhibitor, can produce symptomatic acidosis and bone marrow suppression by a mechanism that is still unknown. This presentation occurs in the elderly, patients with renal or liver failure, people with diabetes, and newborns. The objective of this study was to understand the pathogenic mechanism of these adverse effects and to propose a possible prophylaxis and therapy. METHODS: Four human clinical cases were studied, and one animal experiment was performed. Four preterm newborns with posthemorrhagic ventricular dilation developed severe metabolic acidosis after treatment with acetazolamide. The acidosis suddenly disappeared after a packed red blood cell transfusion. Metabolic studies were performed in one patient and in newborn guinea pigs treated with 200 mg/kg acetazolamide. RESULTS: Acetazolamide can produce severe lactic acidosis with an increased lactate-to-pyruvate ratio, ketosis with a low beta-hydroxybutyrate-to-acetoacetate ratio, and a urinary organic acid profile typical of pyruvate carboxylase deficiency. The acquired enzymatic injury resulting from the inhibition of mitochondrial carbonic anhydrase V that provides bicarbonate to pyruvate carboxylase can produce tricarboxylic acid cycle damage. We demonstrate that the dramatic disappearance of metabolic acidosis and normalizing metabolism after blood transfusion were due to the citrate contained in the packed red blood cell bag. This hypothesis was confirmed by animal experimentation. We argue that the metabolic disorder and bone marrow suppression may be related. CONCLUSION: We demonstrate how acetazolamide can lead to symptomatic metabolic acidosis and probably to bone marrow suppression. We suggest citrate as a possible prophylaxis and treatment for these adverse reactions.