Mitochondrial dysfunction in myotonic dystrophy type 1.

The pathophysiological mechanism linking the nucleotide expansion in the DMPK gene to the clinical manifestations of myotonic dystrophy type 1 (DM1) is still unclear. In vitro studies demonstrate DMPK involvement in the redox homeostasis of cells and the mitochondrial dysfunction in DM1, but in vivo investigations of oxidative metabolism in skeletal muscle have provided ambiguous results and have never been performed in the brain. Twenty-five DM1 patients (14M, 39 ± 11years) underwent brain proton MR spectroscopy (1H-MRS), and sixteen cases (9M, 40 ± 13 years old) also calf muscle phosphorus MRS (31P-MRS). Findings were compared to those of sex- and age-matched controls. Eight DM1 patients showed pathological increase of brain lactate and, compared to those without, had larger lateral ventricles (p < 0.01), smaller gray matter volumes (p < 0.05) and higher white matter lesion load (p < 0.05). A reduction of phosphocreatine/inorganic phosphate (p < 0.001) at rest and, at first minute of exercise, a lower [phosphocreatine] (p = 0.003) and greater [ADP] (p = 0.004) were found in DM1 patients compared to controls. The post-exercise indices of muscle oxidative metabolism were all impaired in DM1, including the increase of time constant of phosphocreatine resynthesis (TC PCr, p = 0.038) and the reduction of the maximum rate of mitochondrial ATP synthesis (p = 0.033). TC PCr values correlated with the myotonic area score (ρ = 0.74, p = 0.01) indicating higher impairment of muscle oxidative metabolism in clinically more affected patients. Our findings provide clear in vivo evidence of multisystem impairment of oxidative metabolism in DM1 patients, providing a rationale for targeted treatment enhancing energy metabolism.

Recurrent De Novo and Biallelic Variation of ATAD3A, Encoding a Mitochondrial Membrane Protein, Results in Distinct Neurological Syndromes.

ATPase family AAA-domain containing protein 3A (ATAD3A) is a nuclear-encoded mitochondrial membrane protein implicated in mitochondrial dynamics, nucleoid organization, protein translation, cell growth, and cholesterol metabolism. We identified a recurrent de novo ATAD3A c.1582C>T (p.Arg528Trp) variant by whole-exome sequencing (WES) in five unrelated individuals with a core phenotype of global developmental delay, hypotonia, optic atrophy, axonal neuropathy, and hypertrophic cardiomyopathy. We also describe two families with biallelic variants in ATAD3A, including a homozygous variant in two siblings, and biallelic ATAD3A deletions mediated by nonallelic homologous recombination (NAHR) between ATAD3A and gene family members ATAD3B and ATAD3C. Tissue-specific overexpression of borR534W, the Drosophila mutation homologous to the human c.1582C>T (p.Arg528Trp) variant, resulted in a dramatic decrease in mitochondrial content, aberrant mitochondrial morphology, and increased autophagy. Homozygous null bor larvae showed a significant decrease of mitochondria, while overexpression of borWT resulted in larger, elongated mitochondria. Finally, fibroblasts of an affected individual exhibited increased mitophagy. We conclude that the p.Arg528Trp variant functions through a dominant-negative mechanism that results in small mitochondria that trigger mitophagy, resulting in a reduction in mitochondrial content. ATAD3A variation represents an additional link between mitochondrial dynamics and recognizable neurological syndromes, as seen with MFN2, OPA1, DNM1L, and STAT2 mutations.

A longitudinal study of a family with adult-onset autosomal dominant leukodystrophy: Clinical, autonomic and neuropsychological findings.

BACKGROUND AND PURPOSE: Adult-onset autosomal dominant leukodystrophy (ADLD) is a rare progressive neurological disorder caused by Lamin B1 duplication (LMNB1). Our aim was to investigate longitudinally the pattern of the autonomic dysfunction and the degree of neuropsychological involvement. METHODS: Three related ADLD patients and one asymptomatic carrier of LMNB1 duplication underwent a standardized evaluation of autonomic nervous system, including cardiovascular reflexes, pharmacological testing, microneurography, skin biopsy, Metaiodobenzylguanidine scintigraphy and a complete neuropsychological battery. RESULTS: An early neurogenic orthostatic hypotension was detected in all patients and confirmed by a low rise in noradrenaline levels on Tilt Test. However infusion of noradrenaline resulted in normal blood pressure rise as well as the infusion of clonidine. At the insulin tolerance test the increase in adrenaline resulted pathological in two out three patients. Microneurography failed to detect muscle sympathetic nerve activity bursts. Skin biopsy revealed a poor adrenergic innervation, while cardiac sympathetic nerves were normal. None of ADLD patients showed a global cognitive deficit but a selective impairment in the executive functions. CONCLUSION: Autonomic disorder in ADLD involves selectively the postganglionic sympathetic system including the sympatho-adrenal response. Cognitive involvement consisting in an early impairment of executive tasks that might precede brain MR abnormalities.

The Cooperative Health Research in South Tyrol (CHRIS) study: rationale, objectives, and preliminary results.

The Cooperative Health Research In South Tyrol (CHRIS) study is a population-based study with a longitudinal lookout to investigate the genetic and molecular basis of age-related common chronic conditions and their interaction with life style and environment in the general population. All adults of the middle and upper Vinschgau/Val Venosta are invited, while 10,000 participants are anticipated by mid-2017. Family participation is encouraged for complete pedigree reconstruction and disease inheritance mapping. After a pilot study on the compliance with a paperless assessment mode, computer-assisted interviews have been implemented to screen for conditions of the cardiovascular, endocrine, metabolic, genitourinary, nervous, behavioral, and cognitive system. Fat intake, cardiac health, and tremor are assessed instrumentally. Nutrient intake, physical activity, and life-course smoking are measured semi-quantitatively. Participants are phenotyped for 73 blood and urine parameters and 60 aliquots per participant are biobanked (cryo-preserved urine, DNA, and whole and fractionated blood). Through liquid-chromatography mass-spectrometry analysis, metabolite profiling of the mitochondrial function is assessed. Samples are genotyped on 1 million variants with the Illumina HumanOmniExpressExome array and the first data release including 4570 fully phenotyped and genotyped samples is now available for analysis. Participants' follow-up is foreseen 6 years after the first visit. The target population is characterized by long-term social stability and homogeneous environment which should both favor the identification of enriched genetic variants. The CHRIS cohort is a valuable resource to assess the contribution of genomics, metabolomics, and environmental factors to human health and disease. It is awaited that this will result in the identification of novel molecular targets for disease prevention and treatment.

The association between restless legs syndrome, cardiovascular and metabolic diseases: hypotheses and evidence from the literature.

The association between RLS and both CVRFs, such as hypertension and diabetes, and CVDs still remains elusive. Although several shared physiopathological causes could explain these possible relationships, the emerging body of literature focusing on these disorders remains controversial. The reasons for these inconsistent findings are mainly due to the different methodologies applied. First, considering that RLS, CVRFs and CVDs are influenced by age and sex, many clinical and population-based studies performed a selection bias by restricting the sample collection to these covariates. Second, assessments of covariates are often incomparable and the methods applied for diseases assessment are often affected by low sensitivity and specificity. Only few population-based studies collected data by means of face-to-face interview or physical examination in order to limit the false positive rate compared to questionnaires administered by mail or telephone. The assessment of RLS was not always performed according to IRLSSG criteria and anyway the four diagnostic criteria did not allow the exclusion of other disorders that may act as mimics (Hening et al., 2009; Allen et al., 2014). Disease assessment ranged from a self-reported diagnosis, information on the use of specific medications, or a direct measurement of BP and blood glucose levels. Moreover, some antihypertensive medications, such as beta-blockers and certain calcium channel blockers, could both ameliorate and aggravate RLS symptoms (Innes et al., 2012) and therefore it would be important to consider medications as confounding factors. In addition, the co-occurrence of several CVRFs is frequent and they may influence each other. Therefore, the cross-sectional nature of most studies cannot assess the causal relationship between them and the variables of interest (i.e., RLS and/ or CVDs). Finally, only few studies adjusted their analyses for other cardiovascular risk factors, such as diabetes mellitus, history of myocardial infarction, BMI, dyslipidemia, and smoking status, that might act as confounders or mediators. In summary, longitudinal population-based studies and meta-analyses will be necessary in order to build a sufficiently robust body of evidence on this topic.

Self-help group and medication overuse headache: preliminary data.

The objective of the study is to investigate the benefits of joining a self-help group for patients with medication overuse headache (MOH). A self-help group is a voluntary gathering of a small number of persons who share a common problem. Little is known about support groups for people with chronic non-malignant pain such as MOH. Eight patients with refractory MOH attended a self-help group twice a month. During the meetings, patients were asked to focus on their headache experiences. Our data showed an increase in resourcefulness in coping with pain and a reduction in cephalalgiophobia. All patients reported general benefits in sharing their headache-related problems. No differences were found for headache frequency or analgesic overuse. To our knowledge, this is the first report on a self-help group for patients with MOH. Joining a self-help group can help patients develop positive attitudes to managing pain.