Sara Galbiati

Vascular endothelial growth factor gene variability is associated with increased risk for AD

Converging evidence points to a pivotal role of vascular endothelial growth factor (VEGF) in neuronal protection and a lack of its activity in neurodegenerative disorders. To investigate this possible association, we screened the VEGF gene promoter for various well‐known single‐nucleotide polymorphisms in a series of 249 consecutively recruited Italian patients with sporadic Alzheimers disease (AD). Genetic analysis indicated different distributions of two single‐nucleotide polymorphisms in the AD population compared with healthy control subjects. In particular, the frequencies of −2578A/A and −1198C/T genotypes were significantly greater in AD patients than in control subjects (23.7 vs 14.7% and 2.8 vs 0%, respectively). The −2578A/A genotype was associated with an increased risk for disease, independently of apolipoprotein E genotype. The risk was significantly increased with respect to various VEGF genotype combinations. In contrast, no difference in serum VEGF levels was detected comparing 96 patients and 49 control subjects. These findings suggest that polymorphisms within the promoter region of the VEGF gene confer greater risk for AD, probably by reducing its neuroprotective effect, and confirm the biological role of VEGF in neurodegenerative processes. Ann Neurol 2005;57:373–380

β-enolase deficiency, a new metabolic myopathy of distal glycolysis

A severe muscle enolase deficiency, with 5% of residual activity, was detected in a 47‐year‐old man affected with exercise intolerance and myalgias. No rise of serum lactate was observed with the ischemic forearm exercise. Ultrastructural analysis showed focal sarcoplasmic accumulation of glycogen β particles. The enzyme enolase catalyzes the interconversion of 2‐phosphoglycerate and phosphoenolpyruvate. In adult human muscle, over 90% of enolase activity is accounted for by the β‐enolase subunit, the protein product of the ENO3 gene. The β‐enolase protein was dramatically reduced in the muscle of our patient, by both immunohistochemistry and immunoblotting, while α‐enolase was normally represented. The ENO3 gene of our patient carries two heterozygous missense mutations affecting highly conserved amino acid residues: a G467A transition changing a glycine residue at position 156 to aspartate, in close proximity to the catalytic site, and a G1121A transition changing a glycine to glutamate at position 374. These mutations were probably inherited as autosomal recessive traits since the mother was heterozygous for the G467A and a sister was heterozygous for the G1121A transition. Our data suggest that ENO3 mutations result in decreased stability of mutant β‐enolase. Muscle β‐enolase deficiency should be considered in the differential diagnosis of metabolic myopathies due to inherited defects of distal glycolysis.

A New Mitochondrial DNA Mutation in ND3 Gene Causing Severe Leigh Syndrome with Early Lethality

We describe a new mitochondrial DNA mutation in a male infant who presented clinical and magnetic resonance imaging features of Leigh syndrome and died at the age of 9 mo. The patients development was reportedly normal in the first months of life. At the age of 5 mo, he presented severe generalized hypotonia, nystagmus, and absent eye contact. Laboratory examination showed increased lactate and pyruvate in both serum and cerebrospinal fluid. Brain magnetic resonance imaging revealed multiple necrotic lesions in the basal ganglia, brain stem, and thalamus. Muscle histopathology was unremarkable, whereas respiratory chain enzyme analysis revealed a severe complex I deficiency. The patient died after an acidotic coma at age 9 mo. Sequence analysis of the entire mtDNA disclosed a new T10158C mutation with variable tissue heteroplasm (muscle: 83%; blood: 48%). The mutation was undetectable in the blood of his unaffected mother. The transition changes a serine residue into a proline, in a highly conserved region of the NADH dehydrogenase subunit 3 (ND3). This is the first description of a mitochondrial ND3 gene in Leigh syndrome with early lethality.

Is M129V of PRNP gene associated with Alzheimer's disease? A case-control study and a meta-analysis.

The methionine/valine (M/V) polymorphism at codon 129 within the prion protein gene (PRNP) represents a known risk factor for Creutzfeldt-Jakob disease (CJD). Few authors reported also the effects of this polymorphism on the risk of Alzheimers disease (AD), although with controversial results. To better clarify this issue, we performed a novel case-control study and a meta-analysis of published association studies between PRNP and AD. Our findings argue against PRNP as a susceptibility gene for developing AD in the Italian population but support the hypothesis that the V allele influences cognitive performances. The meta-analysis, revealed that Caucasian subjects homozygous at codon 129 had a 1.3-fold increased risk [95% CI: 1.0-1.6, p = 0.05] of developing AD compared to heterozygous individuals. We also observed that MM genotype and M allele represent a risk factor for AD, independently from the ethnic background, providing a significant but modest association between this polymorphism and AD.

A missense mutation in the mitochondrial ND5 gene associated with a Leigh-MELAS overlap syndrome.

A 13084 A->T missense mutation in the mitochondrial ND5 gene was identified in a 16-year-old boy affected with a progressive neurodegenerative disorder combining features of Leigh and MELAS (mitochondrial encephalomyopathy, lactic acidosis, and strokelike episodes) syndromes. Muscle biopsy analysis revealed partial complex I deficiency. The mutation presented a variable degree of heteroplasmy in the patient’s tissues. This finding underlines the contribution of mtDNA-encoded complex I subunits in the etiology of complex I deficiency associated with encephalopathy.

Skeletal muscle gene expression profiling in mitochondrial disorders

Extremely variable clinic and genetic features characterize mitochondrial encephalomyopathy (MEM). Pathogenic mitochondrial DNA (mtDNA) defects can be divided into large‐scale rearrangements and single point mutations. Clinical manifestations become evident when a threshold percentage of the total mtDNA is mutated. In some MEM, the “mutant load” in an affected tissue is directly related to the severity of the phenotype. However, the clinical phenotype is not simply a direct consequence of the relative abundance of mutated mtDNA. Other factors, such as nuclear background, can contribute to the disease process, resulting in a wide range of phenotypes caused by the same mutation. Using Affymetrix oligonucleotide cDNA microarrays (HG‐U133A), we studied the gene expression profile of muscle tissue biopsies obtained from 12 MEM patients [4 common 4977 bp deleted mtDNA and 8 A3243G: 4 progressive external ophthalmoplegia (PEO) and 4 mitochondrial myopathy, encephalopathy, lactic cidosis, and stroke‐like episodes syndrome (MELAS) phenotypes] compared with age‐matched healthy individuals. We found several differentially expressed genes: 35 were markedly up‐regulated in the mtDNA macro‐deletion group (vs. the control group) and 4 decreased; 56 genes were dysregulated in A3243G‐related disorders (53 down‐regulated in PEO and 3 up‐regulated in MELAS). Finally, 12 genes were similarly regulated in the majority of the MEM patients under study. Amongst these, we identified an increased expression of genes related to the metabolism of the amino groups, as well as of several genes involved in genetic information processing. Moreover, few genes were similarly decreased in MEM patients vs. the control group. Real‐time PCR demonstrated excellent reproducibility of the microarray‐based findings. The observed expression changes are likely to represent a molecular signature for mitochondrial disorders. Furthermore, the differential expression profile of MELASA3243G vs. PEOA3243G may support a role of nuclear background in contributing to these different clinical phenotypes. MEM microarray data are available from GEO database (http://www.ncbi.nlm.nih.gov/geo/) with the accession number: GSE1462.

A CAV3 microdeletion differentially affects skeletal muscle and myocardium.

To the Editor: In their article, Cagliani et al. observed a 40% reduction of caveolin-3 in the myocardium of a single patient and concluded that this mutation affects skeletal muscle and myocardium differentially. The findings raise concerns. Was cardiac involvement absent in the patients because there were no comprehensive cardiac investigations? At least history, clinical cardiologic examination, ECG, echocardiography, and 24hour ECG are necessary to assess cardiac involvement. Only rudimentary data of these investigations were provided for Patients III-1, III-4, and IV-1. Since cardiac involvement may also develop during the disease course, it is important to regularly follow up. Reduced myocardial caveolin-3 in Patient III-1 may be independent of the underlying mutation and could be also influenced by coronary heart disease or extracorporal circulation during surgery. In rabbits, chronic myocardial hypoxia increased nitric oxide synthase and simultaneously reduced caveolin-3. Was myocardial biopsy taken from a region supplied by a stenosed or normal coronary artery? Was the microdeletion also detected in the myocardium? Possibly hyper-CK-emia in Patient III-2 erroneously led to the diagnosis of myocardial infarction, although the patient died from cardiac involvement in caveolinopathy. Did Patient III-1 have myocardial thickening from arterial hypertension? Since caveolin-3 reduction manifests in the skeletal muscle with various different phenotypes, CI may be also heterogeneous, even within a single family. How do the authors explain that caveolin-3 knockout mice develop severe cardiomyopathy with hypertrophic cardiomyocytes, while humans with caveolin-3 mutations seem to show few cardiac abnormalities? How is it explained that increased nitric oxide synthase results in decrease of caveolin-3 and the development of hypertrophic cardiomyopathy in mice but not in humans? That reduction of caveolin-3 leads to cardiomyopathy is supported by inhibition of hypertrophy of rat cardiomyocytes by adenovirus-mediated overexpression of caveolin-3. On the contrary, overexpression of caveolin-3 induces severe cardiomyopathy in mice. Which are the modifying factors that led to muscle but not to cardiac disease? Figure 4 shows the muscle of a control subject. Did all control subjects undergo muscle biopsy? Atypical absences in Patient IV-1 may be associated with the expression of caveolin-3 also in endothelial cells and astrocytes of the brain. Besides skeletal muscle, myocardium, and brain, caveolin-3 also occurs in the smooth muscle. Did the authors find involvement also of smooth musclecontaining organs? To demonstrate cardiac involvement in caveolinopathies, thorough cardiologic examination, regular follow-ups, and investigations not only of a single patient but all mutation carriers are required.

A mitochondrial tRNAHis gene mutation causing pigmentary retinopathy and neurosensorial deafness

We have identified a heteroplasmic G to A mutation at position 12,183 of the mitochondrial transfer RNA Histidine (tRNAHis) gene in three related patients. These phenotypes varied according to mutation heteroplasmy: one had severe pigmentary retinopathy, neurosensorial deafness, testicular dysfunction, muscle hypotrophy, and ataxia; the other two had only retinal and inner ear involvement. The mutation is in a highly conserved region of the TψC stem of the tRNAHis gene and may alter secondary structure formation. This is the first described pathogenic, maternally inherited mutation of the mitochondrial tRNAHis gene.

Mitochondrial A12308G polymorphism affects clinical features in patients with single mtDNA macrodeletion

Mitochondrial (mt)DNA alterations cause cellular energy failure and respiratory chain dysfunction. Single large-scale rearrangements represent the most common mtDNA mutations and are responsible for very variable clinical manifestations. Here, we show an increased frequency of the A12308G substitution, a common polymorphism used to define the European mtDNA haplogroup U, in mitochondrial patients carrying mtDNA single macrodeletion. In this group of patients, A12308G substitution is associated with a higher relative risk of developing pigmentary retinal degeneration, short stature, dysphasia–dysarthria and cardiac conduction defects. MtDNA haplotype might modulate the clinical expression of mitochondrial encephalomyopathies due to mtDNA macrodeletions.

Paroxysmal Sympathetic Hyperactivity in Pediatric Rehabilitation: Clinical Factors and Acute Pharmacological Management.

Objective:Paroxysmal sympathetic hyperactivity (PSH) is widely described as occurring during intensive care, but in a number of patients it may last longer into the rehabilitation phase. Furthermore, drug therapy has been based on isolated observations. In this study, our aims are to describe a group of 26 pediatric rehabilitation patients with PSH and to quantify the effect of several drugs used to suppress PSH episodes. Setting:Neurorehabilitation unit of IRCCS Eugenio Medea, Bosisio Parini (LC), Italy. Participants:A total of 407 pediatric patients with postacute acquired brain injury, 26 of which had PSH. Design:Retrospective cohort study. Main Measures:Descriptive demographic and clinical data. Odds ratios quantification of the efficacy of drug therapies administered acutely to suppress PSH episodes. Results:PSH was associated with a longer duration of coma and a greater incidence of death. When administered acutely to suppress PSH episodes, the best drugs were clonazepam, hydroxyzine, and delorazepam, while analgesic drugs showed little efficacy. Conclusions:PSH, whether causative or not, is associated with a worse long-term course in rehabilitation. Clinical management of PSH may be helped by a number of acutely administered drug therapies.