Circulating microRNAs in Huntington's disease: Emerging mediators in metabolic impairment.

Huntington's disease (HD) is a hereditary neurodegenerative disease, with peripheral consequences that negatively contribute to quality of life. Circulating microRNAs (cmiRNAs) are being explored for their roles in intercellular communication and gene expression regulation, which allows gaining insight into the regulation of crosstalk between neuronal and peripheral tissues. Here, we explore the cmiRNA profile of plasma samples from fifteen symptomatic patients, with 40-45 CAG repeats in the HTT gene, and seven healthy matched controls. Isolated miRNAs from plasma samples were run against human miRNome panels, which have sequences for 752 human mature miRNAs. We found that 168 cmiRNAs are altered in symptomatic patients. Considering Bonferroni's correction, miR-877-5p, miR-223-3p, miR-223-5p, miR-30d-5p, miR-128, miR-22-5p, miR-222-3p, miR-338-3p, miR-130b-3p, miR-425-5p, miR-628-3p, miR-361-5p, miR-942 are significantly increased in HD patients as compared with controls. Moreover, after patient's organization according to approved HD scales, miR-122-5p is significantly decreased in HD patients with Unified Huntington's Disease Rating Scale >24, whereas an increase in miR-100-5p levels and a decrease in miR-641 and miR-330-3p levels were recorded when patients were rearranged by Total Functional Capacity. These results suggest that cmiRNA profile could be further modified by disease progression, making cmiRNAs useful as monitoring biomarkers. Analysis of target genes indicated a general overexpression of cmiRNAs implicated in metabolism regulation. Profiling cmiRNA of HD subjects opens the possibility of personalized therapies for different groups of HD patients, based on disease modifiers: regulation of altered pathways might contribute to not only alleviate disease symptoms, but also influence HD progression.

A double mutation (A8296G and G8363A) in the mitochondrial DNA tRNA (Lys) gene associated with myoclonus epilepsy with ragged-red fibers.

OBJECTIVE: To define potential pathogenic mitochondrial DNA (mtDNA) point mutations in a patient with myoclonus epilepsy with ragged-red fibers (MERRF) syndrome. BACKGROUND: MERRF syndrome is typically associated with point mutations in the mtDNA tRNALys gene. METHODS: We performed morphologic, biochemical, and genetic analysis of muscle samples from the patient and four relatives. Molecular genetic studies included sequencing, PCR, and restriction enzyme analysis on whole muscle, blood, and single muscle fibers. RESULTS: Muscle biopsy showed cytochrome c oxidase (COX), negative ragged-red fibers (RRF), and a defect of complex I of the mitochondrial respiratory chain. We found an A8296G transition and a G8363A mutation in the mtDNA tRNALYs gene. The A8296G was almost homoplasmic in muscle and blood from the propositus and his oligosymptomatic maternal relatives. The G8363A mutation was heteroplasmic and more abundant in muscle than in blood, and its proportion correlated with clinical severity. Single muscle fiber analysis showed significantly higher levels of G8363A genomes in COX-negative than in normal fibers, and almost homoplasmic levels of mutant A8296G mtDNA in both COX-negative and normal fibers. The two mutations affect highly conserved nucleotides and were not found in controls. CONCLUSIONS: The G8363A mutation is pathogenic; the co-occurrence of the A8296G mutation is of unclear significance and is likely to be a rare polymorphism.

Two pathogenic mutations in the mitochondrial DNA tRNA Leu(UUR) gene (T3258C and A3280G) resulting in variable clinical phenotypes.

We studied two patients with ragged-red fibers and combined defects of the mitochondrial respiratory chain in their muscle biopsy. One had mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes, and harbored a T3258C transition in the tRNA(Leu(UUR)) gene. The other showed myopathy plus cardiomyopathy and had an A3280G mutation in the same gene. Both mutations were heteroplasmic, abundant in muscle of the patients, less abundant in blood, and still less abundant in blood from their maternal relatives. In both patients, single muscle fiber analysis revealed greater abundance of mutant genomes in ragged-red fibers than in normal fibers, supporting the pathogenicity of both mutations.

Evolution of juvenile myoclonic epilepsy treated from the outset with sodium valproate.

Sodium valproate (VPA) is considered the first choice drug in juvenile myoclonic epilepsy (JME). We have analysed the long-term evolution of 22 patients treated from the outset with VPA. The following inclusion criteria were applied: (1) unequivocal diagnosis of JME; (2) treatment should be initiated with VPA monotherapy; and (3) follow-up for more than 5 years. Twenty-two patients (15 females, seven males) were studied and their EEG recordings were analysed. Their mean age was 28 years (range: 20-40 years) and their mean follow-up was 7.7 years (range: 5-17 years). Four of them suffered persistent seizures despite optimal VPA dosage and needed the addition of a second drug (lamotrigine in three cases, clobazam in one case). All of our patients who continued their treatment are seizure-free. VPA effectively controlled all seizures in 80% of patients. The discontinuation of drug therapy lead to a very high rate of relapses. With accurate diagnosis and appropriate therapy, seizures in JME can be effectively controlled. VPA is a very effective antiepileptic drug in controlling the seizures of JME, but many patients relapse after VPA discontinuation. Thus, JME may require lifelong therapy.

[Frequency of the APOE-4 allele in Alzheimer's disease and its variation with age in Asturias (Spain)]. / Frecuencia del alelo APOE-4 en la enfermedad de Alzheimer en la población asturiana y su variación con la edad.

BACKGROUND: Patients with late-onset Alzheimer's disease show a higher frequency of the APOE-4 than controls. The usefulness of the APOE genotyping in the diagnosis of the disease is controversial. Recently, an age dependent prevalence of APOE-4 in Alzheimer's disease has been described, with a maximum frequency for patients with an age at onset between 65 and 80 years. Additionally, the APOE-4 frequency in healthy controls is similar among the different age-groups, including healthy octogenarians. These data suggest that APOE-4 determines when and not who will develop the disease. PATIENTS AND METHODS: The APOE genotype was defined following a previously described PCR-protocol. We analysed 120 patients with clinically defined probable Alzheimer's disease and 250 controls from the same Caucasian population (Austrias, Northern Spain). RESULTS: We found a significantly higher frequency of the APOE-4 in patients, compared to controls (p = 0.00001). The prevalence of this allele was 65% among patients with an age at onset 66-70, falling to 36% and 18% in patients younger than 65 and older than 80 years, respectively. The average age (SD) at onset did not differ between the E-44 (69 years), E-34 (73 years) and E-33 (73 years). APOE-4 frequency was similar between the different age-groups of controls, including healthy octogenarians. CONCLUSIONS: In Asturias, APOE genotyping can not be used for the presimptomatic diagnosis of Alzheimer's disease. However, individuals carrying this allele would have a higher probability of developing the disease at an age between 65 and 80 years if they are predisposed (genetically and/or environmentally) to the disease.

[Characteristics of status epilepticus in MELAS. Analysis of four cases]. / Características del estado del mal epiléptico en MELAS. Análisis de cuatro casos.

INTRODUCTION: Clinical characteristics of status epilepticus (SE) as a first manifestation in patients with MELAS who had not previously epileptic episode has been studied little in the literature. OBJECTIVES: Our aim was to analyse precipitating factors, clinical characteristics, EEG and difficulties in the treatment of SE in MELAS. PATIENTS AND METHODS: We studied four cases with ages between 27 an 41 years who began with SE and they had been diagnosed with MELAS during the episode. Case 3 was confirmed by autopsy. Cases 1, 2 and 4 showed a 3243 mtDNA mutation in the lymphocytes. Epileptic seizures had not been present in any previous status case. The precipitating factor in cases 1 and 3 was fever and in case 2 and 4 stress by headache. Moreover in case 2 second status was caused by stress in hyperglycaemic ketoacidosis. All cases were studied with EEG and a brain CT or MRI. RESULTS: All patients started with epilepsia partialis continua that began with partial motor simple seizures, but sometimes progressed to partial complex seizures or secondary tonic clonic seizures. In two cases the initial symptom was migraine with aura, in two cases fever with cephalalgia and in one case diabetes mellitus decompensation. The EEG during a seizure presented a complex pseudoperiodic complex in the temporal-occipital contralateral region that spread to all hemisphere when myoclonus was increased. CONCLUSIONS: SE in MELAS appears in cell stress situation precipitated by hypermetabolic conditions and it provokes claudication in ill mitochondria. In fact, events such as fever, glycemic alterations, hypoxemia or headache that could change the normal mechanism of sequester mitochondrial calcium in the neuron are able to trigger SE. Optimal evolution depends on an improvement of basal metabolic conditions that could precipitate the status. Supplementary folic acid, riboflavin and coenzyme Q 10 can be useful.

LRRK2 mutations are a common cause of Parkinson's disease in Spain.

Pathogenic mutations in the leucine-rich repeat kinase 2 gene (LRRK2; PARK8) have been implicated in autosomal dominant, late-onset parkinsonism. The LRRK2 6055G > A (G2019S) mutation is the most common reported to date, and has been observed in a number of different European populations. So far, only the LRRK2 4321C > G (R1441G) mutation has been identified in the Spanish population. Herein we have assessed the frequency of G2019S in a referral-based series of 225 patients with Parkinson's disease (PD) from the region of Asturias, Northern Spain. The mutant allele was identified in five (2.7%) of the sporadic late-onset patients and was not present in control subjects. All carriers displayed genetic profiles consistent with the same haplotype, as previously reported for Lrrk2 G2019S-positive subjects. None of these patients presented with a family history of parkinsonism at the time of diagnosis. Thus, approximately 5% of sporadic patients with PD from the North of Spain have either Lrrk2 G2019S or R1441G substitutions.

[The efficacy of the valproic acid-ethosuximide combination in the continuous slow point wave syndrome during sleep]. / Eficacia de la asociación ácido valproico-etosuximida en el síndrome de punta-onda lenta continua durante el sueño.

Continuous spikes and waves during slow sleep (CSWS) is a syndrome with a serious prognosis due to the frequent association with neuropsychological dysfunction. It is mandatory to consider this syndrome if an epileptic child suffers from behavioral changes, dysarthria or learning difficulties. We report on two patients with CSWS syndrome with focal abnormalities on the nondominant hemisphere and a proportion of generalized spike-waves discharges in more than 85% of their NREM sleep on the EEG. Both had a good response to the treatment with sodium valproate and ethosuximide at high doses. Both suffered a relapse of their clinical and EEG semiology after withdrawal of their treatment. After restarting treatment they became clinically normal with a normal sleep EEG recording. We propose the association of sodium valproate and ethosuximide for CSWS; this treatment should be maintained until adolescence.

Complex I defect in muscle from patients with Huntington's disease.

We found a variable defect of complex I of the mitochondrial respiratory chain, ranging in severity from 25% to 63% of control values, in muscle of patients with Huntington's disease (HD). The most severe defect was observed in the patient with the greatest expansion of CAG triplets. Muscle morphology showed myopathic changes such as moth-eaten fibers, angulated fibers, increased subsarcolemmal oxidative activities, or an increased number of enlarged mitochondria with abnormal cristae. Multiple mitochondrial DNA deletions were found by polymerase chain reaction (PCR) analysis in muscle of the patient with the most severe defect of complex I. Our data further support the involvement of energetic defects and oxidative damage in muscle of patients with HD.

Association between an alpha(2) macroglobulin DNA polymorphism and late-onset Alzheimer's disease.

An association between a five-base-pair deletion/insertion DNA polymorphism at the alpha(2) macroglobulin gene (A2M) and late-onset Alzheimer's disease (LOAD) has been recently described. We developed a PCR assay to analyze this polymorphism in 190 LOAD patients (older than 65 years) and 400 controls from Spain. Controls were stratified into three groups: <65 years (n = 200), 65 to 80 years (n = 100), and 81 years or older (n = 100). We found a significantly higher frequency of carriers of the D allele in patients older than 81 years compared to controls older than 81 years (p = 0.0012). In addition, the frequency of the D allele was significantly lower in controls older than 81 years compared to controls younger than 65 (p = 0.048). Our work suggests that the D allele confers an age-dependent increased risk to develop late-onset Alzheimer's disease.

Angiotensin converting enzyme and endothelial nitric oxide synthase DNA polymorphisms and late onset Alzheimer's disease.

OBJECTIVES: Several lines of evidence suggest that the endothelial constitutive nitric oxide synthase (ecNOS) and angiotensin converting enzyme (ACE) may have a role in Alzheimer's disease. ACE is widely expressed in the brain, and a DNA polymorphism at the ACE gene has been linked to the risk for late onset Alzheimer's disease. Nitric oxide (NO) production by microglial cells, astrocytes, and brain microvessels is enhanced in patients with Alzheimer's disease. There is a growing evidence that NO is involved in neuronal death in Alzheimer's disease, and the oxidative stress caused by NO in the brain could be a pathogenic mechanism in Alzheimer's disease. The objective was to determine if two DNA polymorphisms at the ecNOS and ACE genes that have been linked with different levels of enzyme expression, have some effect on the risk of developing late onset Alzheimer disease. METHODS: A total of 400 healthy controls younger than 65 years and 350 patients with Alzheimer's disease (average age 72 years) were genotyped for the ACE and ecNOS polymorphisms. To define a possible role for these polymorphisms in longevity 117 healthy controls older than 85 years were also analysed. Genomic DNA was obtained and amplified by polymerase chain reaction, and genotypes were defined following a previously described procedure. Gene and genotype frequencies between patients and controls were compared statistically. RESULTS: Gene and genotype frequencies for the ecNOS and ACE polymorphisms did not differ between both groups of healthy controls (<65 years and >85 years). EcNOS gene and genotype frequencies were similar between patients and controls. There was a slight but significantly increased frequency of the ACE-I allele among patients with Alzheimer's disease compared with controls (p=0.03; OR=1.28, 95%CI= 1.04;1.58). CONCLUSIONS: The ACE-I allele was associated with a slightly increased risk of developing late onset Alzheimer's disease.