ABSTRACT
Genetic counselors are healthcare professionals who are trained in both medical genetics and counseling to help guide individuals through what is known about genetic predispositions toward a variety of diseases, how they are inherited, and what impact this information can have on them and their partners and families. The range and scope of practice of GC has greatly expanded beyond where it started and now, it is employed in a variety of clinical and research settings. The traditional approach to GC involves meeting with a counselor in person. However, with the increasing availability of online resources, more people are seeking information about genetic disorders online. This shift has led to the development of online GC services. Indeed, genetic counselors are no strangers to improvements in terms of adopting digital solutions in their clinical routine, however, there are few studies assessing genetic counselors' attitudes regarding existing digital tools. Genome Access® is a digital platform that improves patient knowledge in the field of genetic diseases and supports specialists throughout different stages of counseling. This study aims to present Genome Access and discuss the importance of adopting digital technologies designed specifically for GC and what tools these solutions should include.
Subject(s)
Genetic Counseling , Genetic Predisposition to Disease , Humans , Health Personnel , InternetABSTRACT
Human ring chromosomes (RCs) are rare diseases with an estimated newborn incidence of 1/50,000 and an annual occurrence of 2,800 patients globally. Over the past 60 years, banding cytogenetics, fluorescence in situ hybridization (FISH), chromosome microarray analysis (CMA), and whole-genome sequencing (WGS) has been used to detect an RC and further characterize its genomic alterations. Ring syndrome featuring sever growth retardation and variable intellectual disability has been considered as general clinical presentations for all RCs due to the cellular losses from the dynamic mosaicism of RC instability through mitosis. Cytogenomic heterogeneity ranging from simple complete RCs to complex rearranged RCs and variable RC intolerance with different relative frequencies have been observed. Clinical heterogeneity, including chromosome-specific deletion and duplication syndromes, gene-related organ and tissue defects, cancer predisposition to different types of tumors, and reproductive failure, has been reported in the literature. However, the patients with RCs reported in the literature accounted for less than 1% of its occurrence. Current diagnostic practice lacks laboratory standards for analyzing cellular behavior and genomic imbalances of RCs to evaluate the compound effects on patients. Under-representation of clinical cases and lack of comprehensive diagnostic analysis make it a challenge for evidence-based interpretation of clinico-cytogenomic correlations and recommendation of follow-up clinical management. Given recent advancements in genomic technologies and organized efforts by international collaborations and patient advocacy organizations, the prospective of standardized cytogenomic diagnosis and evidence-based clinical management for all patients with RCs could be achieved at an unprecedented global scale.
ABSTRACT
Counseling after WES/WGS presents challenges for healthcare providers as the availability of consumer-driven is rapidly increasing. The present report uncovers an extremely rare homozygous nonsense mutation c. 1639C>T (p.Gln547Ter) in PRX gene of a patient with heterogeneous manifestation of Charcot-Marie-Tooth. Such studies can help to conduct genetic counseling and subsequently more accurate support to individual cases with neuro-genetic conditions and solved through whole genome/exome-wide screening.
ABSTRACT
BACKGROUND: Poland syndrome (OMIM: 173800) is a disorder in which affected individuals are born with missing or underdeveloped muscles on one side of the body, resulting in abnormalities that can affect the chest, breast, shoulder, arm, and hand. The extent and severity of the abnormalities vary among affected individuals. MAIN BODY: The aim of this work is to provide recommendations for the diagnosis and management of people affected by Poland syndrome based on evidence from literature and experience of health professionals from different medical backgrounds who have followed for several years affected subjects. The literature search was performed in the second half of 2019. Original papers, meta-analyses, reviews, books and guidelines were reviewed and final recommendations were reached by consensus. CONCLUSION: Being Poland syndrome a rare syndrome most recommendations here presented are good clinical practice based on the consensus of the participant experts.
Subject(s)
Poland Syndrome , Consensus , Health Personnel , Humans , Poland Syndrome/diagnosisABSTRACT
BACKGROUND: Poland Syndrome (PS) is a rare congenital malformation involving functional and aesthetic impairments. Early diagnosis and timely therapeutic approaches play an important role in improving the quality of life of patients and kindred. This study aims to explore healthcare experiences of the diagnosis of patients affected by PS and to investigate the factors associated with diagnostic delay in Italy. RESULTS: Seventy-two patients affected by PS were asked to fill in a self- administered questionnaire on: a) diagnostic path; b) perceived quality of care received after diagnosis; c) knowledge of the rights and the socio-economic hardships related to their disease; d) evaluation of the integration of various professional skills involved in the diagnostic and therapeutic approach; e) perception of the social support provided by the Italian Association of Poland Syndrome (AISP). The average age at diagnosis was around 14 years; diagnosis was made at birth in only 31.58% of cases. Although typical symptomatology had appeared on average at an early age (4 months), only 23 patients (40.35%) received an early diagnosis (within the first year of life). Just over half of the patients (n = 30) were diagnosed in their region of origin, while 27 were diagnosed elsewhere. Furthermore, 12.28% were self-diagnoses. Among the patients who were diagnosed outside their region, 15 (88.24%) stated they had foregone some visits or treatments owing to costs and/or organizational issues. CONCLUSIONS: An analysis of the patients' experiences highlights several gaps and a lack of homogeneity in the diagnostic and therapeutic follow-up of PS patients in Italy. A specific national diagnostic and therapeutic path is essential to guarantee patients complete and appropriate health services, compliant with the ethical principles of non-discrimination, justice and empathy. Implementation of an effective information and research network and empowerment of patients' associations are necessary conditions to encourage clinical collaboration and improve the quality of life of people living with rare diseases.
Subject(s)
Poland Syndrome/diagnosis , Adolescent , Adult , Child , Female , Humans , Italy , Logistic Models , Male , Pilot Projects , Surveys and Questionnaires , Young AdultABSTRACT
BACKGROUND: Ring chromosome 14 syndrome is a rare chromosomal disorder characterized by early onset refractory epilepsy, intellectual disability, autism spectrum disorder and a number of diverse health issues. RESULTS: The aim of this work is to provide recommendations for the diagnosis and management of persons affected by ring chromosome 14 syndrome based on evidence from literature and experience of health professionals from different medical backgrounds who have followed for several years subjects affected by ring chromosome 14 syndrome. The literature search was performed in 2016. Original papers, meta-analyses, reviews, books and guidelines were reviewed and final recommendations were reached by consensus. CONCLUSION: Conventional cytogenetics is the primary tool to identify a ring chromosome. Children with a terminal deletion of chromosome 14q ascertained by molecular karyotyping (CGH/SNP array) should be tested secondarily by conventional cytogenetics for the presence of a ring chromosome. Early diagnosis should be pursued in order to provide medical and social assistance by a multidisciplinary team. Clinical investigations, including neurophysiology for epilepsy, should be performed at the diagnosis and within the follow-up. Following the diagnosis, patients and relatives/caregivers should receive regular care for health and social issues. Epilepsy should be treated from the onset with anticonvulsive therapy. Likewise, feeding difficulties should be treated according to need. Nutritional assessment is recommended for all patients and nutritional support for malnourishment can include gastrostomy feeding in selected cases. Presence of autistic traits should be carefully evaluated. Many patients with ring chromosome 14 syndrome are nonverbal and thus maintaining their ability to communicate is always essential; every effort should be made to preserve their autonomy.
Subject(s)
Autism Spectrum Disorder/genetics , Caregivers , Chromosome Disorders/genetics , Chromosomes, Human, Pair 14/genetics , Cytogenetics , Humans , Ring ChromosomesABSTRACT
The EuroBioBank (EBB) network (www.eurobiobank.org) is the first operating network of biobanks in Europe to provide human DNA, cell and tissue samples as a service to the scientific community conducting research on rare diseases (RDs). The EBB was established in 2001 to facilitate access to RD biospecimens and associated data; it obtained funding from the European Commission in 2002 (5th framework programme) and started operation in 2003. The set-up phase, during the EC funding period 2003-2006, established the basis for running the network; the following consolidation phase has seen the growth of the network through the joining of new partners, better network cohesion, improved coordination of activities, and the development of a quality-control system. During this phase the network participated in the EC-funded TREAT-NMD programme and was involved in planning of the European Biobanking and Biomolecular Resources Research Infrastructure. Recently, EBB became a partner of RD-Connect, an FP7 EU programme aimed at linking RD biobanks, registries, and bioinformatics data. Within RD-Connect, EBB contributes expertise, promotes high professional standards, and best practices in RD biobanking, is implementing integration with RD patient registries and 'omics' data, thus challenging the fragmentation of international cooperation on the field.
Subject(s)
Biological Specimen Banks/organization & administration , Rare Diseases/genetics , Registries , Computational Biology , Europe , Humans , International Cooperation , Quality Control , Rare Diseases/diagnosis , Rare Diseases/pathology , Rare Diseases/therapyABSTRACT
Access to biological materials is a key prerequisite for scientific research in any medical field and in particular for research into rare diseases (RDs), for which obtaining high-quality samples and the related clinical data remains a major hurdle. RD biobanks play a pivotal role in making such materials and data available to the scientific community. In order to increase the effectiveness of RD biobanks, three major challenges need to be met: maximise access to rare biological samples stored in RD biobanks spread globally by the international scientific community, promote networking among such biobanks to share quality standards and procedures and allow collaboration with RD registries and databases, and finally adopt an efficient management model compliant with legal and ethical issues and ensuring biobank sustainability. The European program RD-Connect, funded under the FP7 program, addresses all of these issues through an articulated action plan aimed at building a network of European RD biobanks. Ultimately, RD-Connect will offer access to precious, quality-controlled biological samples from RD patients through an online, searchable, dynamic catalogue in the context of an integrated platform that links RD patient registries to biobanks and to clinical bioinformatics data for RD research.
Subject(s)
Biological Specimen Banks , Databases, Factual , Rare Diseases , Research , Specimen Handling , Animals , Europe , HumansABSTRACT
Maternal inheritance of mtDNA is the rule in most animals, but the reasons for this pattern remain unclear. To investigate the consequence of overriding uniparental inheritance, we generated mice containing an admixture (heteroplasmy) of NZB and 129S6 mtDNAs in the presence of a congenic C57BL/6J nuclear background. Analysis of the segregation of the two mtDNAs across subsequent maternal generations revealed that proportion of NZB mtDNA was preferentially reduced. Ultimately, this segregation process produced NZB-129 heteroplasmic mice and their NZB or 129 mtDNA homoplasmic counterparts. Phenotypic comparison of these three mtDNA lines demonstrated that the NZB-129 heteroplasmic mice, but neither homoplasmic counterpart, had reduced activity, food intake, respiratory exchange ratio; accentuated stress response; and cognitive impairment. Therefore, admixture of two normal but different mouse mtDNAs can be genetically unstable and can produce adverse physiological effects, factors that may explain the advantage of uniparental inheritance of mtDNA.
Subject(s)
DNA, Mitochondrial/genetics , Mice/genetics , Animals , Behavior, Animal , Cognition , Female , Inheritance Patterns , Male , Mice/physiology , Mice, 129 Strain , Mice, Inbred C57BL , Mice, Inbred NZB , Species SpecificityABSTRACT
UNLABELLED: Polymorphisms in the interleukin-28B (IL28B) region are associated with spontaneous and treatment-induced viral clearance in hepatitis C virus (HCV) infection. Nevertheless, it is unknown whether genetic variation at the IL28B locus influences the natural history of chronic HCV infection. Thus, we asked whether an association between IL28B polymorphisms and liver fibrosis progression existed. We studied 247 consecutive patients with chronic HCV, an accurate estimate of the date of infection, and a liver biopsy performed before any treatment. No patient had a history of alcohol abuse or coinfection with other viruses. We assessed the role of rs8099917 and rs12979860 polymorphisms and the effect of host and environmental factors on fibrosis progression. Blood transfusion (75%) was the main modality of infection. Median age at infection was 21 years, and median interval between infection and liver biopsy was 25 years. One hundred twenty-nine patients (52%) were infected by HCV-1, 74 (30%) by HCV-2, 34 (14%) by HCV-3, and 10 (4%) by HCV-4. Bridging fibrosis/cirrhosis (Ishak ≥ 4) was detected in 24% of patients. Age at infection had a marked effect on fibrosis progression by both a linear model and Cox proportional-hazard regression (P < 2E-16). A 12.1% increase in the hazard of advanced fibrosis was estimated for each additional year at infection, suggesting that this was the major explanatory variable in this cohort. Male gender (P < 0.05), HCV genotype 3 (P < 0.001) and steatosis (P < 0.05) were also associated with faster fibrosis progression. Conversely, the two IL28B polymorphisms had no impact on fibrosis progression. CONCLUSION: In HCV patients with a known date of infection, IL28B genotype was not associated with fibrosis progression rate or with the risk of developing advanced liver fibrosis.
Subject(s)
Disease Progression , Genetic Variation , Hepatitis C, Chronic/genetics , Interleukins/genetics , Liver Cirrhosis/genetics , Adult , Age Distribution , Age of Onset , Cohort Studies , Female , Follow-Up Studies , Genotype , Hepatitis C, Chronic/epidemiology , Hepatitis C, Chronic/pathology , Humans , Interferons , Linear Models , Liver Cirrhosis/epidemiology , Liver Cirrhosis/pathology , Liver Cirrhosis/virology , Male , Middle Aged , Proportional Hazards Models , Severity of Illness Index , Sex Distribution , Young AdultABSTRACT
The impact of anti-TNF therapy on systemic immune responses in patients has not been clearly defined. Here, we examined Th1/Th2/Th17 cytokine expression, activation and proliferation of peripheral T cells from patients with psoriasis and inflammatory bowel disease before and during anti-TNF therapy. In parallel, we calculated the correlation with the clinical response and we monitored cytokine expression in biopsies from inflamed tissues. We evidenced a dual role of TNF-blockade. In peripheral blood, it increased the expression of cytokines such as IL-17, IL-10, and IFN-γ, and enhanced the expression of activation markers and the proliferative response of CD4 T cells to TCR stimulation. By contrast, in biopsies from target tissues, TNF-blockade diminished the expression of Th17/Th1 cytokine and early inflammatory genes. Importantly, the enhanced T cell responses to TCR-stimulation did not impair the clinical response to the therapy and, in responder patients, occurred with the concomitant down-regulation of inflammatory genes in the target tissues.
Subject(s)
Blood/immunology , Lymphocyte Activation/drug effects , Psoriasis/drug therapy , Receptors, Antigen, T-Cell/metabolism , Skin/immunology , T-Lymphocytes/drug effects , Tumor Necrosis Factor-alpha/antagonists & inhibitors , Adalimumab , Adolescent , Adult , Aged , Aged, 80 and over , Anti-Inflammatory Agents, Non-Steroidal/pharmacology , Anti-Inflammatory Agents, Non-Steroidal/therapeutic use , Antibodies, Monoclonal/pharmacology , Antibodies, Monoclonal/therapeutic use , Antibodies, Monoclonal, Humanized , Antigens, CD/genetics , Antigens, CD/metabolism , B-Lymphocytes/cytology , B-Lymphocytes/metabolism , Bacterial Toxins/immunology , Blood/drug effects , Blood/metabolism , CD4-Positive T-Lymphocytes/cytology , CD4-Positive T-Lymphocytes/drug effects , CD4-Positive T-Lymphocytes/immunology , CD4-Positive T-Lymphocytes/metabolism , Cell Proliferation/drug effects , Cytokines/blood , Cytokines/genetics , Cytokines/metabolism , Enterotoxins/immunology , Etanercept , Female , Gene Expression/drug effects , Gene Expression/immunology , Humans , Immunoglobulin G/pharmacology , Immunoglobulin G/therapeutic use , Inflammation/drug therapy , Inflammation/immunology , Inflammation/metabolism , Inflammatory Bowel Diseases/drug therapy , Inflammatory Bowel Diseases/immunology , Inflammatory Bowel Diseases/metabolism , Infliximab , Leukocytes, Mononuclear/drug effects , Leukocytes, Mononuclear/immunology , Leukocytes, Mononuclear/metabolism , Lymphocyte Activation/immunology , Male , Middle Aged , Psoriasis/immunology , Psoriasis/metabolism , Receptors, Tumor Necrosis Factor/therapeutic use , Skin/drug effectsABSTRACT
Mitochondria are semi-autonomously reproductive organelles within eukaryotic cells carrying their own genetic material, called the mitochondrial genome (mtDNA). Until some years ago, mtDNA had primarily been used as a tool in population genetics. As scientists began associating mtDNA mutations with dozens of mysterious disorders, as well as the aging process and a variety of chronic degenerative diseases, it became increasingly evident that the information contained in this genome had substantial potential applications to improve human health. Today, mitochondria research covers a wide range of disciplines, including clinical medicine, biochemistry, genetics, molecular cell biology, bioinformatics, plant sciences and physiology. The present review intends to present a summary of the most exiting fields of the mitochondrial research bringing together several contributes in terms of original prospective and future applications.
Subject(s)
DNA, Mitochondrial/genetics , Genome, Mitochondrial/genetics , Mitochondrial Diseases/genetics , Models, Genetic , Animals , Genetic Predisposition to Disease/genetics , HumansABSTRACT
Mitochondrial deoxyribonucleic acid depletion syndromes are autosomal recessive disorders characterized by a reduction of the amount of mitochondrial deoxyribonucleic acid, which impairs the synthesis of respiratory chain complexes. Mutations in the deoxyguanosine kinase and polymerase gamma genes have been identified in hepatocerebral forms, whereas thymidine kinase 2 gene mutations have been found in patients with isolated myopathy, encephalomyopathy, or spinal muscular atrophy. Mutations in the gene encoding the beta subunit of the adenosine diphosphate-forming succinyl-coenzyme A synthetase have also been reported in a family. In this report, the clinical, molecular, morphologic, and biochemical features of five children from two independent families with an infantile encephalomyopathy are characterized. The affected children manifested muscle mitochondrial deoxyribonucleic acid depletion and three novel thymidine kinase 2 gene mutations. They consist of a homozygous substitution resulting in Ala to Val change at the highly conserved position 181 of thymidine kinase in the first family, and two heterozygous substitutions in the second family: a Cys to Trp change at residue 108 and a Leu to Pro change at residue 257 of the enzyme. Common clinical features associated with these TK2 mutations are a normal early developmental phase followed by psychomotor regression, encephalopathy often with epileptic seizures, and myopathy with features of a progressive dystrophic process.
Subject(s)
Chromosome Aberrations , DNA Mutational Analysis , DNA, Mitochondrial/genetics , Genes, Recessive/genetics , Mitochondrial Encephalomyopathies/genetics , Thymidine Kinase/genetics , Amino Acid Substitution/genetics , Biopsy , Child , Child, Preschool , Diagnosis, Differential , Disease Progression , Electron Transport Complex IV/genetics , Epilepsy/diagnosis , Epilepsy/genetics , Female , Genetic Carrier Screening , Genotype , Homozygote , Humans , Infant , Male , Mitochondrial Encephalomyopathies/diagnosis , Muscle, Skeletal/pathology , Phenotype , Psychomotor Disorders/diagnosis , Psychomotor Disorders/geneticsABSTRACT
Spinal muscular atrophy with respiratory distress type 1 (SMARD1) is an infantile autosomal-recessive motor neuron disease caused by mutations in the immunoglobulin micro-binding protein 2. We investigated the potential of a spinal cord neural stem cell population isolated on the basis of aldehyde dehydrogenase (ALDH) activity to modify disease progression of nmd mice, an animal model of SMARD1. ALDH(hi)SSC(lo) stem cells are self-renewing and multipotent and when intrathecally transplanted in nmd mice generate motor neurons properly localized in the spinal cord ventral horns. Transplanted nmd animals presented delayed disease progression, sparing of motor neurons and ventral root axons and increased lifespan. To further investigate the molecular events responsible for these differences, microarray and real-time reverse transcription-polymerase chain reaction analyses of wild-type, mutated and transplanted nmd spinal cord were undertaken. We demonstrated a down-regulation of genes involved in excitatory amino acid toxicity and oxidative stress handling, as well as an up-regulation of genes related to the chromatin organization in nmd compared with wild-type mice, suggesting that they may play a role in SMARD1 pathogenesis. Spinal cord of nmd-transplanted mice expressed high transcript levels for genes related to neurogenesis such as doublecortin (DCX), LIS1 and drebrin. The presence of DCX-expressing cells in adult nmd spinal cord suggests that both exogenous and endogenous neurogeneses may contribute to the observed nmd phenotype amelioration.
Subject(s)
Gene Expression Regulation , Motor Neurons/cytology , Spinal Cord/metabolism , Spinal Muscular Atrophies of Childhood/physiopathology , Stem Cell Transplantation , Stem Cells/metabolism , 1-Alkyl-2-acetylglycerophosphocholine Esterase , Aldehyde Dehydrogenase/metabolism , Animals , Blotting, Western , Cells, Cultured , Disease Progression , Doublecortin Domain Proteins , Doublecortin Protein , Immunohistochemistry , Mice , Mice, Mutant Strains , Microarray Analysis , Microtubule-Associated Proteins/metabolism , Neuropeptides/metabolism , Reverse Transcriptase Polymerase Chain Reaction , Spinal Cord/cytology , Stem Cells/cytology , Survival AnalysisABSTRACT
A 45-year-old male patient had an episode of acute renal failure with myoglobinuria, myalgias, weakness, and markedly increased serum CK levels. Similar episodes had occurred in the past. Carnitine palmitoyl-transferase II (CPT II) deficiency was documented both biochemically and genetically. Interestingly, muscle biopsy also showed some ragged red fibers (RRF) and complete mitochondrial DNA (mtDNA) sequence disclosed a homoplasmic T3394C point mutation. This mutation is described in Leber's hereditary optic neuropathy (LHON) or in patients with diabetes mellitus.
Subject(s)
Carnitine O-Palmitoyltransferase/deficiency , DNA, Mitochondrial/genetics , Mitochondrial Diseases/enzymology , Mitochondrial Diseases/genetics , Muscular Diseases/enzymology , Point Mutation/genetics , Acute Kidney Injury/etiology , Acute Kidney Injury/physiopathology , Base Sequence/genetics , Biopsy , Carnitine O-Palmitoyltransferase/genetics , Creatine Kinase/blood , DNA Mutational Analysis , Humans , Male , Middle Aged , Mitochondrial Diseases/physiopathology , Muscle Fibers, Skeletal/enzymology , Muscle Fibers, Skeletal/pathology , Muscle Weakness/enzymology , Muscle Weakness/genetics , Muscle Weakness/physiopathology , Muscle, Skeletal/enzymology , Muscle, Skeletal/pathology , Muscle, Skeletal/physiopathology , Muscular Diseases/complications , Muscular Diseases/physiopathology , Myoglobinuria/etiology , Myoglobinuria/physiopathology , SyndromeABSTRACT
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 Alzheimer's 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.
Subject(s)
Alzheimer Disease/genetics , Genetic Predisposition to Disease , Risk , Vascular Endothelial Growth Factors/genetics , Aged , Aged, 80 and over , Alzheimer Disease/blood , Chi-Square Distribution , Confidence Intervals , Female , Genotype , Humans , Male , Molecular Biology/methods , Polymorphism, Single Nucleotide/genetics , Promoter Regions, Genetic/genetics , Retrospective Studies , Vascular Endothelial Growth Factors/bloodABSTRACT
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 MELAS(A3243G) vs. PEO(A3243G) 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.
Subject(s)
Gene Expression Profiling , Mitochondrial Encephalomyopathies/genetics , Muscle, Skeletal/metabolism , Adolescent , Adult , Biopsy , DNA, Mitochondrial/analysis , DNA, Mitochondrial/genetics , Female , Gene Deletion , Gene Dosage , Gene Expression Regulation , Humans , MELAS Syndrome/genetics , Male , Middle Aged , Muscle, Skeletal/chemistry , Mutation , Oligonucleotide Array Sequence Analysis , Phenotype , RNA, Messenger/analysis , Reproducibility of Results , Reverse Transcriptase Polymerase Chain ReactionABSTRACT
Mitochondria are ubiquitous in eukaryotic cells where they generate much of the cellular energy by the process of oxidative phosphorylation (OXPHOS). The approximately 1500 genes of the mitochondrial genome are distributed between the cytoplasmic, maternally-inherited, mitochondrial DNA (mtDNA) which encodes 37 genes and the nuclear DNA (nDNA) which encompasses the remaining mitochondrial genes. The interplay between the mtDNA and nDNA encoded mitochondrial genes and their role in mitochondrial disorders is still largely unclear. One approach for elucidating the pathophysiology of mitochondrial diseases has been to look at changes in the expression of mtDNA and nDNA-encoded genes in response to specific mitochondrial genetic defects. Initial studies of gene expression changes in response to mtDNA defect employed blot technologies to analyze changes in the expression of individual genes one at a time. While Southern/Northern blot experiments confirmed the importance of nDNA-mtDNA interactions in the pathophysiology of mitochondrial myopathy, the methodology used limited the number of genes that could be analyzed from each patient. This barrier has been overcome, in part by the advent of DNA microarray technology. In DNA microarrays gene sequences or oligonucleotides homologous to gene sequences are arrayed on a solid support. The RNA from the subject is then isolated, the mRNA converted to cDNA and the cDNA labeled with a fluorescent probe. The labeled cDNA is hybridized on the microarray and the fluorescence bound to each array is then quantified. Recently, these technologies have been applied to mitochondrial disease patient tissues and the presence of coordinate changes in mitochondrial gene expression confirmed.
Subject(s)
DNA, Mitochondrial/genetics , Gene Expression Regulation , Mitochondrial Diseases/genetics , Mitochondrial Diseases/physiopathology , Oligonucleotide Array Sequence Analysis/methods , HumansABSTRACT
Dysferlin plays an essential role in the muscle repair machinery, and its deficiency is associated with limb-girdle muscular dystrophy type 2B and with two different distal myopathies (Miyoshi myopathy and distal anterior compartment myopathy). Our aims were to characterize the pattern of dysferlin expression during myogenic cell differentiation and to assess possible differentially spliced isoforms of the DYSF gene. Human primary myogenic cells express a splice variant of dysferlin mRNA lacking exon 17 (Delta17), together with full-length dysferlin mRNA. Real-time polymerase chain reaction analysis of human myoblasts, myotubes, and normal skeletal muscle showed that Delta17 expression inversely correlates with muscle differentiation. Indeed, Delta17 is progressively replaced by the wild type as myoblast fusion proceeds, and it disappears in adult skeletal muscle. Conversely, Delta17 is the predominant dysferlin variant in mature peripheral nerve. Our findings suggest that the two proteins play different roles in myogenic cell differentiation and that dysferlin function in peripheral nerve might be accomplished by this novel isoform.