Educational interventions in pharmacovigilance to improve the knowledge, attitude and the report of adverse drug reactions in healthcare professionals: Systematic Review and Meta-analysis.

OBJECTIVES: Underreporting of adverse drug reactions (ADRs) limits and delays the detection of signs. The aim of this systematic review with meta-analyses was to synthesize the evidence of educational interventions (EIs) efficacy in health professionals to increase ADR reporting, attitudes, and knowledge of pharmacovigilance. EVIDENCE ACQUISITION: A systematic literature review was carried out to identify randomized clinical trials evaluating the efficacy of EI in pharmacovigilance in health professionals to improve ADR reports, knowledge, and attitude toward pharmacovigilance. ADR reports were pooled by calculating Odds Ratio (OR) with a 95% confidence interval (95%CI), while pharmacovigilance knowledge and attitude were pooled by calculating a mean difference (MD) with 95%CI. In addition, the subanalysis was performed by EI type. Meta-analysis was performed with RevMan 5.4 software. PROSPERO registry CRD42021254270. RESULTS: Eight hundred seventy-five articles were identified as potentially relevant, and 11 were included in the systematic review. Metanalysis showed that EI increased ADR reporting in comparison with control group (OR = 4.74, [95%CI, 2.46 to 9.12], I2 = 93%, 5 studies). In subgroup analysis, the workshops (OR = 6.26, [95%CI, 4.03 to 9.73], I2 = 57%, 3 studies) increased ADR reporting more than telephone-based interventions (OR = 2.59, [95%CI, 0.77 to 8.73], I2 = 29%, 2 studies) or combined interventions (OR = 5.14, [95%CI, 0.97 to 27.26], I2 = 93%, 3 studies). No difference was observed in pharmacovigilance knowledge. However, the subanalysis revealed that workshops increase pharmacovigilance knowledge (SMD = 1.85 [95%CI, 1.44 to 2.27], 1 study). Only one study evaluated ADR reporting attitude among participants and showed a positive effect after the intervention. CONCLUSION: EI improves ADR reports and increases pharmacovigilance knowledge. Workshops are the most effective EI to increase ADR reporting.

Structural variation analysis of 6,500 whole genome sequences in amyotrophic lateral sclerosis.

There is a strong genetic contribution to Amyotrophic lateral sclerosis (ALS) risk, with heritability estimates of up to 60%. Both Mendelian and small effect variants have been identified, but in common with other conditions, such variants only explain a little of the heritability. Genomic structural variation might account for some of this otherwise unexplained heritability. We therefore investigated association between structural variation in a set of 25 ALS genes, and ALS risk and phenotype. As expected, the repeat expansion in the C9orf72 gene was identified as associated with ALS. Two other ALS-associated structural variants were identified: inversion in the VCP gene and insertion in the ERBB4 gene. All three variants were associated both with increased risk of ALS and specific phenotypic patterns of disease expression. More than 70% of people with respiratory onset ALS harboured ERBB4 insertion compared with 25% of the general population, suggesting respiratory onset ALS may be a distinct genetic subtype.

Telomere length analysis in amyotrophic lateral sclerosis using large-scale whole genome sequence data.

Background: Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the loss of upper and lower motor neurons, leading to progressive weakness of voluntary muscles, with death following from neuromuscular respiratory failure, typically within 3 to 5 years. There is a strong genetic contribution to ALS risk. In 10% or more, a family history of ALS or frontotemporal dementia is obtained, and the Mendelian genes responsible for ALS in such families have now been identified in about 50% of cases. Only about 14% of apparently sporadic ALS is explained by known genetic variation, suggesting that other forms of genetic variation are important. Telomeres maintain DNA integrity during cellular replication, differ between sexes, and shorten naturally with age. Sex and age are risk factors for ALS and we therefore investigated telomere length in ALS. Methods: Samples were from Project MinE, an international ALS whole genome sequencing consortium that includes phenotype data. For validation we used donated brain samples from motor cortex from people with ALS and controls. Ancestry and relatedness were evaluated by principal components analysis and relationship matrices of DNA microarray data. Whole genome sequence data were from Illumina HiSeq platforms and aligned using the Isaac pipeline. TelSeq was used to quantify telomere length using whole genome sequence data. We tested the association of telomere length with ALS and ALS survival using Cox regression. Results: There were 6,580 whole genome sequences, reducing to 6,195 samples (4,315 from people with ALS and 1,880 controls) after quality control, and 159 brain samples (106 ALS, 53 controls). Accounting for age and sex, there was a 20% (95% CI 14%, 25%) increase of telomere length in people with ALS compared to controls (p = 1.1 × 10-12), validated in the brain samples (p = 0.03). Those with shorter telomeres had a 10% increase in median survival (p = 5.0×10-7). Although there was no difference in telomere length between sporadic ALS and familial ALS (p=0.64), telomere length in 334 people with ALS due to expanded C9orf72 repeats was shorter than in those without expanded C9orf72 repeats (p = 5.0×10-4). Discussion: Although telomeres shorten with age, longer telomeres are a risk factor for ALS and worsen prognosis. Longer telomeres are associated with ALS.

European mitochondrial haplogroups are associated with CD4+ T cell recovery in HIV-infected patients on combination antiretroviral therapy.

BACKGROUND: There is substantial interindividual variability in the rate and extent of CD4+ T cell recovery after starting combination antiretroviral therapy (cART). The aim of our study was to determine whether mitochondrial DNA (mtDNA) haplogroups are associated with recovery of CD4+ in HIV-infected patients on cART. METHODS: We carried out a retrospective study on 275 cART-naive patients with CD4+ counts <350 cells/mm(3), who were followed-up during at least 24 months after initiating cART. mtDNA genotyping was performed by Sequenom's MassARRAY platform. RESULTS: Patients within cluster JT and haplogroup J had a lower chance of achieving a CD4+ count ≥500 cells/mm(3) than patients within cluster HV and haplogroup H [hazard ratio (HR) = 0.68 (P = 0.058) and HR = 0.48 (P = 0.010), respectively]. The time of follow-up during which the CD4+ count was ≥500 cells/mm(3) was longer in haplogroups HV and H than in haplogroups JT and J [20 months versus 6.2 months (P = 0.029) and 20 months versus 0 months (P = 0.024), respectively]. Additionally, haplogroups HV and H had greater chances of achieving a CD4+ count ≥500 cells/mm(3) during at least 12, 36, 48 and 60 months post-cART initiation compared with patients within haplogroups JT and J. Patients within haplogroup T only had a lesser chance of achieving a CD4+ count ≥500 cells/mm(3) during at least 48 months and 60 months post-cART initiation. CONCLUSION: European mitochondrial haplogroups might influence CD4+ recovery in HIV-infected patients following initiation with cART. Haplogroups J and T appear to be associated with a worse profile of CD4+ recovery, whereas haplogroup H was associated with a better CD4+ reconstitution.

Mitochondrial haplogroups are associated with clinical pattern of AIDS progression in HIV-infected patients.

We performed a cross-sectional study in 469 HIV-infected patients, whose mitochondrial haplogroups were genotyped to study their association with the clinical pattern of AIDS progression. The chance of not having an AIDS progression was 1.45 [95% of confidence interval (CI) = 1.02 to 2.05, P = 0.035) times greater in patients with cluster HV and 1.51 (95% CI = 1.06 to 2.18, P = 0.021) times greater in patients with haplogroup H. However, we only found significant values for haplogroup H (odds ratio = 1.52, 95% CI = 1.01 to 2.32, P = 0.049) in an ordinal logistic regression adjusted by gender, age at HIV infection, intravenous drug users, and hepatitis C virus infection. These data suggest that mitochondrial haplogroups might play a significant role in AIDS progression.

Clinical and cellular consequences of the mutation m.12300G>A in the mitochondrial tRNA(Leu(CUN)) gene.

We report, for the first time, a patient with an overlap MERRF-NARP syndrome who carries the mutation m.12300G>A in the mitochondrial tRNA(Leu(CUN)) gene. The mutation was heteroplamic and more abundant in her muscle and fibroblast than in blood from her oligosymptomatic mother. Single muscle fiber analysis revealed that the proportion of mutant mtDNA in ragged red fibers was higher than that in normal fibers. Combined defects of mitochondrial respiratory chain complexes were detected in muscle, fibroblasts and transmitochondrial hybrid cells. Significant reduction of total ATP and mitochondrial membrane potential and an increased production of reactive oxygen species were observed.

European mitochondrial DNA haplogroups and metabolic disorders in HIV/HCV-coinfected patients on highly active antiretroviral therapy.

BACKGROUND: Mitochondrial DNA (mtDNA) haplogroups play an important role in susceptibility to metabolic disorders and cardiovascular disease. METHODS: We carried out a cross-sectional study in 248 HIV/hepatitis C virus-coinfected patients on highly active antiretroviral therapy to investigate whether mtDNA haplogroups had any influence on metabolic disorders. mtDNA genotyping was performed using the Sequenom MassARRAY platform. Insulin resistance (IR) was estimated using the homeostatic model assessment (HOMA) (HOMA ≥ 3.8), which was calculated as fasting plasma glucose (mmol/L) times fasting serum insulin (mU/L) divided by 22.5. A high atherogenic risk was assessed when the atherogenic index (AI) was ≥3.5. AI was calculated as total cholesterol (mg/dL) divided by HDL (mg/dL). RESULTS: The major haplogroup HV and haplogroup H had reduced odds ratios of IR (HOMA ≥ 3.8) [0.45 (95% CI: 0.24 to 0.85) and 0.36 (95% CI: 0.18 to 0.69), respectively], and high AI (AI ≥ 3.5) [0.44 (95% CI: 0.22 to 0.87) and 0.40 (95% CI: 0.19 to 0.80), respectively]. The major haplogroup U had increased odds of IR [2.66 (95% CI: 1.39 to 5.8)]. The major haplogroup JT and haplogroup T had increased odds of high AI [2.86 (95% CI: 1.29 to 6.33) and 4.01 (95%CI: 1.59 to 10.03), respectively]. Additionally, we found that patients belonging to the major haplogroup HV had lower values of serum hepatic growth factor and nerve growth factor, and higher values of adiponectin than patients belonging to the major haplogroup JT (P < 0.05). CONCLUSIONS: mtDNA haplogroups were associated with IR and atherogenic dyslipidemia; suggesting that mitochondrial genomics may play a significant role in metabolic disorders and cardiovascular diseases in HIV/hepatitis C virus-coinfected patients on highly active antiretroviral therapy.

European mitochondrial DNA haplogroups and liver fibrosis in HIV and hepatitis C virus coinfected patients.

BACKGROUND: HIV infection, hepatitis C virus (HCV) liver disease, and mitochondrial DNA (mtDNA) polymorphisms are three possibly interrelated factors that might be associated with progression of liver disease. The aim of this study was to investigate whether mtDNA haplogroups had any influence on liver fibrosis progression in HIV/HCV coinfected patients. METHODS: We carried out a cross-sectional study in 231 patients who were genotyped via Sequenom's MassARRAY platform (San Diego, California, USA). Liver fibrosis was estimated based on the METAVIR score. In each patient, fibrosis progression rate (FPR) was calculated by dividing the fibrosis stage (0-4) by the estimated duration of HCV infection in years. RESULTS: The cluster or major haplogroup HV was significantly associated with reduced odds ratios (OR) for advanced fibrosis [OR 0.35, 95% confidence interval (CI) 0.16-0.77, P = 0.009], cirrhosis (OR 0.16, 95% CI 0.04-0.60, P = 0.007), or high FPR (OR 0.43, 95% CI 0.21-0.84, P = 0.015). Within the major haplogroup HV, haplogroup H was significantly associated with an absence of advanced fibrosis (OR 0.40, 95% CI 0.18-0.91, P = 0.029), cirrhosis (OR 0.14, 95% CI 0.03-0.67, P = 0.014), or high FPR (OR 0.47, 95% CI 0.23-0.95, P = 0.035). We also found a significant association with increased odds of cirrhosis (OR 5.25, 95% CI 1.76-15.64, P = 0.003) in the closely related major haplogroup U. CONCLUSION: The mtDNA haplogroups HV and H were associated with slower fibrosis progression, and the haplogroup U was associated with faster fibrosis progression in HIV/HCV coinfected patients. These data suggest that mtDNA haplogroup may play a significant role in liver fibrogenesis during HCV infection.

Cyfip1 is a putative invasion suppressor in epithelial cancers.

Identification of bona fide tumor suppressors is often challenging because of the large number of genetic alterations present in most human cancers. To evaluate candidate genes present within chromosomal regions recurrently deleted in human cancers, we coupled high-resolution genomic analysis with a two-stage genetic study using RNA interference (RNAi). We found that Cyfip1, a subunit of the WAVE complex, which regulates cytoskeletal dynamics, is commonly deleted in human epithelial cancers. Reduced expression of CYFIP1 is commonly observed during invasion of epithelial tumors and is associated with poor prognosis in this setting. Silencing of Cyfip1 disturbed normal epithelial morphogenesis in vitro and cooperated with oncogenic Ras to produce invasive carcinomas in vivo. Mechanistically, we have linked alterations in WAVE-regulated actin dynamics with impaired cell-cell adhesion and cell-ECM interactions. Thus, we propose Cyfip1 as an invasion suppressor gene.

Lethal hepatopathy and leukodystrophy caused by a novel mutation in MPV17 gene: description of an alternative MPV17 spliced form.

It has recently been reported that mutations in MPV17 gene may be causative of mtDNA depletion syndrome (MDS). Patients with this alteration presented with severe liver failure, hypoglycemia, growth retardation and neurological symptoms during the first year of life. We report on the clinical, biochemical and molecular findings of a patient presenting with lethal hepatopathy, polyneuropathy, neurological regression and leukodystrophy associated with mutations in MPV17. Mitochondrial respiratory chain activities were low in liver and within reference values in muscle. However, levels of mtDNA were markedly reduced both in muscle and liver. A novel homozygous mutation in MPV17, c.70+5G>A (IVS1+5G>A), was identified. This intronic change causes the full-length cDNA loss, probably due to loss of strength of the splice donor site of exon 1. Western blot analysis, performed in liver homogenates, further corroborates these results as the amount of patient's protein was highly reduced, or almost absent, compared with that of controls. We also identified an additional alternative spliced form in controls and in the patient, due to exon 2 skipping, that has not previously been reported.

OPA1 mutations induce mitochondrial DNA instability and optic atrophy 'plus' phenotypes.

Mutations in OPA1, a dynamin-related GTPase involved in mitochondrial fusion, cristae organization and control of apoptosis, have been linked to non-syndromic optic neuropathy transmitted as an autosomal-dominant trait (DOA). We here report on eight patients from six independent families showing that mutations in the OPA1 gene can also be responsible for a syndromic form of DOA associated with sensorineural deafness, ataxia, axonal sensory-motor polyneuropathy, chronic progressive external ophthalmoplegia and mitochondrial myopathy with cytochrome c oxidase negative and Ragged Red Fibres. Most remarkably, we demonstrate that these patients all harboured multiple deletions of mitochondrial DNA (mtDNA) in their skeletal muscle, thus revealing an unrecognized role of the OPA1 protein in mtDNA stability. The five OPA1 mutations associated with these DOA 'plus' phenotypes were all mis-sense point mutations affecting highly conserved amino acid positions and the nuclear genes previously known to induce mtDNA multiple deletions such as POLG1, PEO1 (Twinkle) and SLC25A4 (ANT1) were ruled out. Our results show that certain OPA1 mutations exert a dominant negative effect responsible for multi-systemic disease, closely related to classical mitochondrial cytopathies, by a mechanism involving mtDNA instability.

Association of novel POLG mutations and multiple mitochondrial DNA deletions with variable clinical phenotypes in a Spanish population.

BACKGROUND: Both dominant and recessive mutations were reported in the gene encoding the mitochondrial (mt) DNA polymerase gamma (POLG) in patients with progressive external ophthalmoplegia (PEO). Phenotypes other than PEO were recently documented in patients with mutations in the POLG gene. OBJECTIVE: To screen patients with mitochondrial disease and multiple mtDNA deletions in muscle for mutations in the coding regions of the POLG, PEO1, and SLC25A4 genes. DESIGN: To identify the underlying molecular defect in a group of patients with multiple mtDNA deletions comparing their molecular genetic findings with those of healthy controls. PATIENTS: Twenty-four patients (16 men and 8 women) diagnosed with mitochondrial disease and having multiple mtDNA deletions in muscle by Southern blot analysis. Thirteen patients had PEO; 2 had PEO alone, 4 had PEO and myopathy, and 5 had PEO and multisystem involvement. Four patients had multisystem disease without PEO. The remaining 9 patients had isolated myopathy. DNA from 100 healthy individuals was also studied. RESULTS: No mutation was identified in the PEO1 or SLC25A4 genes. Nine POLG mutations were observed in 6 of 24 patients. Four novel mutations were detected and mapped in the linker region (M603L) and in the pol domain of the enzyme (R853W; D1184N; R1146C). Five patients with PEO had mutations: 2 were compound heterozygotes, 1 was homozygous, and another showed a mutation in a single allele. The remaining patient also showed a sole mutation and had an unusual phenotype lacking ocular involvement. CONCLUSIONS: POLG molecular defects were found in 25% of our patients with multiple mtDNA deletions and mitochondrial disease. The uncommon phenotype found in 1 of these patients stresses the clinical variability of patients harboring POLG mutations. Molecular studies in the POLG gene should be addressed in patients with mitochondrial disease, particularly in those with PEO, and multiple mtDNA deletions.

Renal pathology in children with mitochondrial diseases.

We studied renal involvement in 42 children with mitochondrial diseases (MDs). The diagnosis of MD was established by morphological, biochemical, and molecular genetic criteria. Renal disease was considered when patients had renal failure, nephrotic syndrome, Fanconi's syndrome or any symptomatic renal alteration. Mild tubular disorder was established if they had abnormal laboratory findings with no apparent clinical symptom. Renal involvement was found in 21 children (50%), of whom 8 had an apparent clinical picture and 13 a mild tubular disorder. Five patients with renal disease showed Debré-Toni-Fanconi's syndrome, 2 of them with decreased glomerular filtration rate (GFR). One case had nephrotic syndrome, another one presented decreased GFR, and the last one had a neurogenic bladder and bilateral hydronephrosis. Patients with mild renal disease showed tubular dysfunction with normal GFR. Renal involvement is frequent and present in about half of the children with MD. Thus, studies for evaluating kidney function should be performed on children with MD. Conversely, patients with tubulopathy of unknown origin or progressive renal disease should be investigated for the existence of MD, especially if associated with involvement of other organs or tissues. Southern blot analysis to search for large-scale mitochondrial DNA (mtDNA) rearrangements should be performed for patients with MD and kidney involvement.

Exercise training in mitochondrial myopathy: a randomized controlled trial.

Patients with mitochondrial myopathies (MM) usually suffer from exercise intolerance due to their impaired oxidative capacity and physical deconditioning. We evaluated the effects of a 12-week supervised randomized rehabilitation program involving endurance training in patients with MM. Twenty MM patients were assigned to a training or control group. For three nonconsecutive days each week, patients combined cycle exercise at 70% of their peak work rate with three upper-body weight-lifting exercises performed at 50% of maximum capacity. Training increased maximal oxygen uptake (28.5%), work output (15.5%), and minute ventilation (40%), endurance performance (62%), walking distance in shuttle walking test (+95 m), and peripheral muscle strength (32%-62%), and improved Nottingham Health Profile scores (21.47%) and clinical symptoms. Control MM patients did not change from baseline. Results show that our exercise program is an adequate training strategy for patients with mitochondrial myopathy.

Specific correlation between the wobble modification deficiency in mutant tRNAs and the clinical features of a human mitochondrial disease.

Mutations in mtDNA are responsible for a variety of mitochondrial diseases, where the mitochondrial tRNA(Leu(UUR)) gene has especially hot spots for pathogenic mutations. Clinical features often depend on the tRNA species and/or positions of the mutations; however, molecular pathogenesis elucidating the relation between the location of the mutations and their leading phenotype are not fully understood. We report here that mitochondrial tRNAs(Leu(UUR)) harboring one of five mutations found in tissues from patients with symptoms of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) (A3243G, G3244A, T3258C, T3271C, and T3291C) lacked the normal taurine-containing modification (5-taurinomethyluridine) at the anticodon wobble position. In contrast, mitochondrial tRNAs(Leu(UUR)) with different mutations found in patients that have mitochondrial diseases but do not show the MELAS symptoms (G3242A, T3250C, C3254T, and A3280G) had the normal 5-taurinomethyluridine modifications. These observations were made by using a modified primer extension technique that can detect the modification deficiency in the extremely limited quantities of mutant tRNAs obtainable from patient tissues. These results strongly suggest deficient wobble modification could be a key molecular factor responsible for the phenotypic features of MELAS, which can explain why the different MELAS-associated mutations result in indistinguishable clinical features.

Leigh syndrome associated with mitochondrial complex I deficiency due to a novel mutation in the NDUFS1 gene.

BACKGROUND: Mutations in the nuclear-encoded subunits of complex I of the mitochondrial respiratory chain are a recognized cause of Leigh syndrome (LS). Recently, 6 mutations in the NDUFS1 gene were identified in 3 families. OBJECTIVE: To describe a Spanish family with LS, complex I deficiency in muscle, and a novel mutation in the NDUFS1 gene. DESIGN: Using molecular genetic approaches, we identified the underlying molecular defect in a patient with LS with a complex I defect. PATIENT: The proband was a child who displayed the clinical features of LS. RESULTS: Muscle biochemistry results showed a complex I defect of the mitochondrial respiratory chain. Sequencing analysis of the mitochondrial DNA-encoded ND genes, the nuclear DNA-encoded NDUFV1, NDUFS1, NDUFS2, NDUFS4, NDUFS6, NDUFS7, NDUFS8, and NDUFAB1 genes, and the complex I assembly factor CIA30 gene revealed a novel homozygous L231V mutation (c.691C-->G) in the NDUFS1 gene. The parents were heterozygous carriers of the L231V mutation. CONCLUSIONS: Identifying nuclear mutations as a cause of respiratory chain disorders will enhance the possibility of prenatal diagnosis and help us understand how molecular defects can lead to complex I deficiency.

Increased mitochondrial respiratory chain enzyme activities correlate with minor extent of liver damage in mice suffering from erythropoietic protoporphyria.

Mitochondrial dysfunction might play a role in the pathogenesis of liver damage in erythropoietic protoporphyria (EPP). Changes in mitochondrial respiratory chain activities were evaluated in the Fech(m1pas)/Fech(m1pas) mouse model for EPP. Mice from different strains congenic for the same ferrochelatase germline mutation manifest variable degrees of hepatobiliary injury. Protoporphyric animals bred into the C57BL/6J background showed a higher degree of hepatomegaly and liver damage as well as higher protoporphyrin (PP) accumulation than those bred into the SJL/J and BALB/cJ backgrounds. Whereas mitochondrial respiratory chain activities remained unchanged in the liver of protoporphyric mice C57BL/6J, they were increased in protoporphyric mice from both SJL/J and BALB/cJ backgrounds, when compared to wild-type animals. Mitochondrial respiratory chain activities were increased in Hep G2 cell line after accumulation of PP following addition of aminolevulinic acid. As a direct effect of these elevated mitochondrial activities, in both hepatic cells from mutant mouse strains and Hep G2 cells, adenosine 5'-triphosphate (ATP) levels significantly increased as the intracellular PP concentration was reduced. These results indicate that PP modifies intracellular ATP requirements as well as hepatic mitochondrial respiratory chain enzymatic activities and further suggest that an increase of these activities may provide a certain degree of protection against liver damage in protoporphyric mice.

Comparative analysis of the pathogenic mechanisms associated with the G8363A and A8296G mutations in the mitochondrial tRNA(Lys) gene.

Two mutations (G8363A and A8296G) in the mtDNA (mitochondrial DNA) tRNA(Lys) gene have been associated with severe mitochondrial diseases in a number of reports. Their functional significance, however, remains unknown. We have already shown that homoplasmic cybrids harbouring the A8296G mutation display normal oxidative phosphorylation, although the possibility of a subtle change in mitochondrial respiratory capacity remains an open issue. We have now investigated the pathogenic mechanism of another mutation in the tRNA(Lys) gene (G8363A) by repopulating an mtDNA-less human osteosarcoma cell line with mitochondria harbouring either this genetic variant alone or an unusual combination of the two mutations (A8296G+G8363A). Cybrids homoplasmic for the single G8363A or the A8296G+G8363A mutations have defective respiratory-chain enzyme activities and low oxygen consumption, indicating a severe impairment of the oxidative phosphorylation system. Generation of G8363A cybrids within a wild-type or the A8296G mtDNA genetic backgrounds resulted in an important alteration in the conformation of the tRNA(Lys), not affecting tRNA steady-state levels. Moreover, mutant cybrids have an important decrease in the proportion of amino-acylated tRNA(Lys) and, consequently, mitochondrial protein synthesis is greatly decreased. Our results demonstrate that the pathogenicity of the G8363A mutation is due to a change in the conformation of the tRNA that severely impairs aminoacylation in the absence of changes in tRNA stability. The only effect detected in the A8296G mutation is a moderate decrease in the aminoacylation capacity, which does not affect mitochondrial protein biosynthesis.

Coenzyme Q 10 improves lactic acidosis, strokelike episodes, and epilepsy in a patient with MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes).

Mitochondrial encephalomyopathies encompass a group of disorders that have impaired oxidative metabolism in skeletal muscles and central nervous system. Many compounds have been used in clinical trials on mitochondrial diseases, but the outcomes have been variable. It remains controversial whether treatment of mitochondrial diseases with coenzyme Q 10 is effective. This paper describes a case of mitochondrial myopathy, encephalopathy, lactic acidosis, strokelike episodes, and exercise intolerance successfully treated with coenzyme Q 10. Efficacy of this therapy in this patient is correlated to control of lactic acidosis and serum creatine kinase levels. Disappointingly, larger studies with coenzyme Q 10 failed to demonstrate a clear beneficial effect on the entire study population with regard to clinical improvement or several parameters of the oxidative metabolism. They suggest that the use of coenzyme Q in treatment of mitochondrial diseases should be confined to protocols. There is a confounding variation in phenotype and genotype, and the natural history of the disorders in individual patients is not accurately predictable. The unpredictable a priori efficacy of therapy suggests that a long-term trial of oral coenzyme Q may be warranted.