Umberto De Girolami

Missense mutations in the rod domain of the lamin A/C gene as causes of dilated cardiomyopathy and conduction-system disease

BACKGROUND Inherited mutations cause approximately 35 percent of cases of dilated cardiomyopathy; however, few genes associated with this disease have been identified. Previously, we located a gene defect that was responsible for autosomal dominant dilated cardiomyopathy and conduction-system disease on chromosome 1p1-q21, where nuclear-envelope proteins lamin A and lamin C are encoded by the LMNA (lamin A/C) gene. Mutations in the head or tail domain of this gene cause Emery-Dreifuss muscular dystrophy, a childhood-onset disease characterized by joint contractures and in some cases by abnormalities of cardiac conduction during adulthood. METHODS We evaluated 11 families with autosomal dominant dilated cardiomyopathy and conduction-system disease. Sequences of the lamin A/C exons were determined in probands from each family, and variants were confirmed by restriction-enzyme digestion. The genotypes of the family members were ascertained. RESULTS Five novel missense mutations were identified: four in the alpha-helical-rod domain of the lamin A/C gene, and one in the lamin C tail domain. Each mutation caused heritable, progressive conduction-system disease (sinus bradycardia, atrioventricular conduction block, or atrial arrhythmias) and dilated cardiomyopathy. Heart failure and sudden death occurred frequently within these families. No family members with mutations had either joint contractures or skeletal myopathy. Serum creatine kinase levels were normal in family members with mutations of the lamin rod but mildly elevated in some family members with a defect in the tail domain of lamin C. CONCLUSIONS Genetic defects in distinct domains of the nuclear-envelope proteins lamin A and lamin C selectively cause dilated cardiomyopathy with conduction-system disease or autosomal dominant Emery-Dreifuss muscular dystrophy. Missense mutations in the rod domain of the lamin A/C gene provide a genetic cause for dilated cardiomyopathy and indicate that this intermediate filament protein has an important role in cardiac conduction and contractility.

Molecular Classification of Low-Grade Diffuse Gliomas

The current World Health Organization classification recognizes three histological types of grade II low-grade diffuse glioma (diffuse astrocytoma, oligoastrocytoma, and oligodendroglioma). However, the diagnostic criteria, in particular for oligoastrocytoma, are highly subjective. The aim of our study was to establish genetic profiles for diffuse gliomas and to estimate their predictive impact. In this study, we screened 360 World Health Organization grade II gliomas for mutations in the IDH1, IDH2, and TP53 genes and for 1p/19q loss and correlated these with clinical outcome. Most tumors (86%) were characterized genetically by TP53 mutation plus IDH1/2 mutation (32%), 1p/19q loss plus IDH1/2 mutation (37%), or IDH1/2 mutation only (17%). TP53 mutations only or 1p/19q loss only was rare (2 and 3%, respectively). The median survival of patients with TP53 mutation ± IDH1/2 mutation was significantly shorter than that of patients with 1p/19q loss ± IDH1/2 mutation (51.8 months vs. 58.7 months, respectively; P = 0.0037). Multivariate analysis with adjustment for age and treatment confirmed these results (P = 0.0087) and also revealed that TP53 mutation is a significant prognostic marker for shorter survival (P = 0.0005) and 1p/19q loss for longer survival (P = 0.0002), while IDH1/2 mutations are not prognostic (P = 0.8737). The molecular classification on the basis of IDH1/2 mutation, TP53 mutation, and 1p/19q loss has power similar to histological classification and avoids the ambiguity inherent to the diagnosis of oligoastrocytoma.

Noninvasive Magnetic Resonance Spectroscopic Imaging Biomarkers to Predict the Clinical Grade of Pediatric Brain Tumors

The diagnosis and therapy of childhood brain tumors, most of which are low grade, can be complicated because of their frequent adjacent location to crucial structures, which limits diagnostic biopsy. Also, although new prognostic biomarkers identified by molecular analysis or DNA microarray gene profiling are promising, they too depend on invasive biopsy. Here, we test the hypothesis that combining information from biologically important intracellular molecules (biomarkers), noninvasively obtained by proton magnetic resonance spectroscopic imaging, will increase the diagnostic accuracy in determining the clinical grade of pediatric brain tumors. We evaluate the proton magnetic resonance spectroscopic imaging exams for 66 children with brain tumors. The intracellular biomarkers for choline-containing compounds (Cho), N-acetylaspartate, total creatine, and lipids and/or lactate were measured at the highest Cho region and normalized to the surrounding healthy tissue total creatine. Neuropathological grading was done with WHO criteria. Normalized Cho and lipids and/or lactate were elevated in high-grade (n = 23) versus low-grade (n = 43) tumors, which multiple logistic regression confirmed are independent predictors of tumor grade (for Cho, odds ratio 24.8, P < 0.001; and for lipids and/or lactate, odds ratio 4.4, P < 0.001). A linear combination of normalized Cho and lipids and/or lactate that maximizes diagnostic accuracy was calculated by maximizing the area under the receiver operating characteristic curve. Proton magnetic resonance spectroscopic imaging, although not a proxy for histology, provides noninvasive, in vivo biomarkers for predicting clinical grades of pediatric brain tumors.

JCV-specific cellular immune response correlates with a favorable clinical outcome in HIV-infected individuals with progressive multifocal leukoencephalopathy

Most immunosuppressed individuals who develop progressive multifocal leukoencephalopathy (PML) have a rapid fatal outcome, whereas some become long-term survivors. We explored the impact of the cellular immune response against JC virus (JCV) on the clinical outcome of 7 HIV+ and 3 HIV−individuals with PML. Of the 4 HIV+/PML survivors, all had detectable cytotoxic T lymphocytes (CTL) specific for JCV T or VP1 proteins compared to none of the 3 HIV+/PML progressors tested. Of the 3 HIV−/PML patients, 1 was recently diagnosed with PML and showed evidence of neurologic improvement without any treatment. This patient had CTL specific for the VP1 protein of JCV. The other 2 HIV−/PML survivors were stable 3–8 years after the diagnosis of PML. They did not have any detectable CTL against JCV. These findings suggest that JCV-specific immune response is associated with favorable outcome in HIV+ individuals with PML. The lack of detectable JCV-specific CTL in 2 HIV−/PML survivors might indicate a burnt-out disease without sufficient antigenic stimulation to maintain the cellular immune response. The detection of JCV-specific CTL in an HIV−patient recently diagnosed with PML, who was showing evidence of neurological improvement without any treatment, indicates that this finding may be used as a favorable prognostic marker of disease evolution in the clinical management of patients with PML. As the quest for an effective treatment of PML continues, JCV-specific cellular immune response deserves further attention because it appears to play a crucial role in the prevention of disease progression.

Lethal neonatal deficiency of carnitine palmitoyltransferase II associated with dysgenesis of the brain and kidneys

We describe neonatal onset of a lethal multiorgan deficiency of carnitine palmitoyltransferase II (CPT II) associated with dysmorphic features, cardiomyopathy, and cystic dysplasia of the brain and kidneys. Concentrations of long-chain acylcarnitines were evaluated in blood and multiple tissues, diffuse lipid accumulation was present at autopsy, and a profound deficiency of CPT II activity was evident in heart, liver, muscle, and kidney tissue. This disorder constitutes another recognizable malformation syndrome with a metabolic basis. Deficiency of CPT II should be included in the differential diagnosis of patients with cystic renal dysplasia, dysmorphism, central nervous system malformations, and early death, along with glutaric acidemia type II, Zellweger syndrome, and other disorders in which peroxisomal beta-oxidation is impaired. The clinicopathologic similarities among these disorders raise the possibility that a common biochemical mechanism, namely the disruption of beta-oxidation of fatty acids, is responsible for the abnormal organogenesis.

Characterization of lymphocytic infiltrates in progressive multifocal leukoencephalopathy: Co-localization of CD8+ T cells with JCV-infected glial cells

We characterized inflammatory infiltrates in archival brain biopsy and autopsy samples from 26 HIV+ and 20 HIV− patients with progressive multifocal leukoencephalopathy (PML). The predominant inflammatory cells were CD8+ T lymphocytes. We defined CD8+ T cell distribution with regard to JCV-infected glial cells, PML lesions and the extent of demyelination. In most samples from either HIV+ and HIV− patients, we found positive correlations between the parenchymal CD8+ T cells and JCV-infected glial cells and conversely, negative correlations between the perivascular CD8+ T cells and JCV-infected glial cells in the surrounding brain. Most of these correlations remained significant after accounting for the degree of demyelination and location of the cells relative to lesions. Moreover, high numbers of CD8+ T cells were found within and at the border of active PML lesions. These results suggest that CD8+ T cells are primarily associated with JCV-infected glial cells in most PML cases and that an active ongoing recruitment of CD8+ T cells and possibly viral antigen-specific retention could occur. These observations are discussed in the context of the recent evidence of PML in multiple sclerosis and Crohn’s patients treated with natalizumab, underscoring the role of CD8+ T lymphocytes in continued immunosurveillance of the CNS.

Neurologic and histopathologic evaluation after high-volume intrathecal amitriptyline

Background and objectives Accumulating evidence indicates that amitriptyline decreases pain sensation when administered orally, intraperitoneally, or for sciatic nerve block. Previous reports of intrathecal administration of amitriptyline have yielded inconsistent results. The failure of amitriptyline to provide antinociception may partly be related to its high logP (octanol-water partition coefficient) and consequent poor spread within the cerebrospinal fluid. We evaluated spinal block after various concentrations of amitriptyline administered intrathecally in a fixed high volume. Methods We administered 100 μL of 5, 10, 15.9 (0.5%), 25, 50, or 100 mmol/L amitriptyline hydrochloride solution or 100 μL of 15.4 mmol/L (0.5%) bupivacaine hydrochloride solution intrathecally to rats. The neurologic deficit was evaluated by antinociceptive, motor, and proprioceptive responses, and the spinal cord was examined for histopathologic changes. Results Doses of 100 μL amitriptyline at 15.9 mmol/L (0.5%) and 25 mmol/L produced longer complete nerve block than did bupivacaine at 15.4 mmol/L (0.5%); 5 and 10 mmol/L amitriptyline produced only partial nerve block. However, with 100 μL intrathecal amitriptyline at 50 and 100 mmol/L, many rats did not fully recover from spinal block. Severe axonal degeneration, myelin breakdown, and replacement of neuronal structures by vacuoles were seen in the spinal root section of animals injected with concentrations higher than 25 mmol/L amitriptyline. Conclusions At lower doses, intrathecal injection of high volumes of amitriptyline results in long-acting spinal block. At higher doses, intrathecal amitriptyline results in irreversible neurologic deficit. Therefore, we do not recommend the use of intrathecal amitriptyline because of a very low therapeutic index.

Neuropathology of sleep disorders: a review.

Sleep disorders are important manifestations of neurodegenerativediseases and sometimes are clinically evident well before the onset of other neurological manifestations. This review addresses theneuroanatomical basis and the mechanisms of sleep regulation in humans in relation to the neuropathology of entities associated with sleep disturbances in selected diseases, including Alzheimer disease, progressive supranuclear palsy, Lewy body disorders, multiple-system atrophy, and fatal familial insomnia. This includes abnormalities of circadian rhythm, insomnia, narcolepsy, rapid eye movements sleep behavior disorders, and excessive daytime sleepiness.

Myotonia in colchicine myoneuropathy

Colchicine may induce a myoneuropathy in patients with renal insufficiency. To date, myotonia has not been described in this disorder. We recently studied 4 patients treated with routine doses of colchicine who, in the setting of renal insufficiency, developed a severe myoneuropathy characterized by prominent myotonic discharges on electromyography. In addition, 1 of the 4 patients had profound clinical myotonia. In the 3 patients in whom biopsies were performed, marked myopathic change with intracytoplasmic vacuolization was identified. All 4 patients improved rapidly with discontinuation of the medication. The patient in whom electrophysiologic studies were repeated had a complete resolution of the myotonic discharges. Colchicine myoneuropathy can present with prominent clinical and electrophysiologic myotonia that resolves completely with discontinuation of the medication.

Collateral nerve fibers in human spinal cord: visualization with magnetic resonance diffusion tensor imaging.

Diffusion tensor magnetic resonance imaging provides structural information about nerve fiber tissue. The first eigenvector of the diffusion tensor is aligned with the nerve fibers, i.e., longitudinally in the spinal cord. The underlying hypothesis of this study is that the presence of collateral nerve fibers running orthogonal to the longitudinal fibers results in an orderly arrangement of the second eigenvectors. Magnetic resonance diffusion tensor scans were performed with line scan diffusion imaging on a clinical MR scanner. Axial sections were scanned in a human cervical spinal cord specimen at 625 microm resolution and the cervical spinal cord of four normal volunteers at 1250 microm resolution. The spinal cord specimen was fixed and stained for later light microscopy of the collateral fiber architecture at 0.53 microm resolution. Diffusion measured by MR was found to be anisotropic for both white and gray matter areas of the spinal cord specimen; the average fractional anisotropy (FA) was 0.63 +/- 0.09 (diffusion eigenvalues lambda1 0.38 +/- 0.05 micros/mm2, lambda2 0.14 +/- 0.03 micros/mm2, lambda3 0.10 +/- 0.03 micros/mm2) in white matter and 0.27 +/- 0.04 (lambda1 0.36 +/- 0.04 micros/mm2, lambda2 0.28 +/- 0.03 micros/mm2, lambda3 0.21 +/- 0.04 micros/mm2 in gray matter. The normal-volunteer FA values were similar, i.e., 0.66 +/- 0.04 (lambda1 1.66 +/- 0.14 micros/mm2, lambda2 0.55 +/- 0.02 micros/mm2, lambda3 0.40 +/- 0.01 micros/mm2) in white matter and 0.35 +/- 0.03 (lambda1 1.14 +/- 0.07 micros/mm2, lambda2 0.70 +/- 0.03 micros/mm2, lambda3 0.58 +/- 0.02 micros/mm2) in gray matter. The first eigenvector pointed, as expected, in the longitudinal direction. The second eigenvector directions exhibited a striking arrangement, consistent with the distribution of interconnecting collateral nerve fibers discerned on the histology section. This finding was confirmed for the specimen by quantitative pixel-wise comparison of second eigenvector directions and collateral fiber directions assessed on light microscopy image data. Diffusion tensor MRI can reveal non-invasively and in great detail the intricate fiber architecture of the human spinal cord.