Reduced cystatin B activity correlates with enhanced cathepsin activity in progressive myoclonus epilepsy

BACKGROUND: Loss-of-function mutations in the gene encoding cystatin B (CSTB) underlie an inherited neurodegenerative disorder, progressive myoclonus epilepsy of Unverricht-Lundborg type (EPM1). CSTB is an inhibitor of several papain-family cysteine proteases, the lysosomal cathepsins. Its physiological function and the molecular pathways leading to the clinical EPM1 phenotype are unknown. AIM: To elucidate the role of CSTB and different cathepsins in pathogenesis of EPM1. METHOD: We determined the total papain inhibitory (cystatin) and papain-like (cathepsin) activity as well as specific activities of cathepsins B, H, L and S in lymphoblastoid cells of EPM1 patients, carriers and controls. RESULTS: In EPM1 patients, who express reduced levels of CSTB mRNA, the papain inhibitory activity was significantly decreased or absent. This reduction was correlated with significant increase in general cathepsin activity. The increase in cathepsin B, L and S activities was highly significant, whereas the increase in cathepsin H activity was not. CONCLUSIONS: This is the first demonstration of cysteine protease activity being regulated by CSTB activity in a biological context. The effects of decreased CSTB activity in EPM1 pathogenesis may, at least in part, be mediated by cathepsins through increased activity of cathepsins S and L.     

Reduced cystatin B activity correlates with enhanced cathepsin activity in progressive myoclonus epilepsy

BACKGROUND: Loss-of-function mutations in the gene encoding cystatin B (CSTB) underlie an inherited neurodegenerative disorder, progressive myoclonus epilepsy of Unverricht-Lundborg type (EPM1). CSTB is an inhibitor of several papain-family cysteine proteases, the lysosomal cathepsins. Its physiological function and the molecular pathways leading to the clinical EPM1 phenotype are unknown. AIM: To elucidate the role of CSTB and different cathepsins in pathogenesis of EPM1. METHOD: We determined the total papain inhibitory (cystatin) and papain-like (cathepsin) activity as well as specific activities of cathepsins B, H, L and S in lymphoblastoid cells of EPM1 patients, carriers and controls. RESULTS: In EPM1 patients, who express reduced levels of CSTB mRNA, the papain inhibitory activity was significantly decreased or absent. This reduction was correlated with significant increase in general cathepsin activity. The increase in cathepsin B, L and S activities was highly significant, whereas the increase in cathepsin H activity was not. CONCLUSIONS: This is the first demonstration of cysteine protease activity being regulated by CSTB activity in a biological context. The effects of decreased CSTB activity in EPM1 pathogenesis may, at least in part, be mediated by cathepsins through increased activity of cathepsins S and L.     

Clinical characteristics and laboratory findings in prion diseases

Acutely progressing dementia, generalized myoclonus, and periodic synchronous discharge (PSD) on EEG are thought to be characteristic features of Creutzfeldt-Jakob disease (CJD). However, recent surveillance studies in European countries and Japan have revealed several uncommon variants that run relatively long clinical course, demonstrate atypical myoclonus, and show no PSD. Brain specific proteins such as 14-3-3 protein, tau protein, and neuron specific enolase (NSE) are detected in the CSF of CJD patients. Clinical features and laboratory findings of sporadic CJD are related well to the combination of polymorphism at codon 129 of prion protein gene(PRNP) (Methionine/Methionine, Methionine/Valine, and Valine/Valine) and type of pathogenic prion protein (type 1 and type 2). Those of genetic prion disease depend on pathogenic mutation in PRNP. Positive rates of PSD and 14-3-3 protein in the CSF differ among subtypes of sporadic CJD and genetic prion diseases. Diffusion-weighted MRI is very useful for an early clinical diagnosis of CJD and some subtypes show their own characteristic findings.     

Molecular diagnostics of genetic eye diseases

Eye diseases can be simple or complex, and mostly of heterogeneous molecular genetics. Some eye diseases are caused by mutations in a single gene, but some diseases, such as primary open angle glaucoma, can be due to sequence variations in multiple genes. In some diseases, both genetic and epigenetic mechanisms are involved, as was recently revealed in the mechanism of retinoblastoma. Disease causative mutations and phenotypes may vary by ethnicity and geography. To date, more than a hundred candidate genes for eye diseases are known, although less than 20 have definite disease-causing mutations. The three common genetic eye diseases, primary open angle glaucoma, age-related macular degeneration, and retinitis pigmentosa, all have known gene mutations, but these account for only a portion of the patients. While the search for eye disease genes and mutations still goes on, known mutations have been utilized for diagnosis. Genetic markers for pre-symptomatic and pre-natal diagnosis are available for specific diseases such as primary open angle glaucoma and retinoblastoma. This paper reviews the molecular basis of common genetic eye diseases and the available genetic markers for clinical diagnosis. Difficulties and challenges in molecular investigation of some eye diseases are discussed. Establishment of ethnic-specific disease databases that contain both clinical and genetic information for identification of genetic markers with diagnostic, prognostic, or pharmacological value is strongly advocated.     

Abnormal reactivity of the approximately 20-Hz motor cortex rhythm in Unverricht Lundborg type progressive myoclonus epilepsy

The approximately 20-Hz component of the human mu rhythm originates predominantly in the primary motor cortex. We monitored with a whole-scalp neuromagnetometer the reactivity of the approximately 20-Hz rhythm as an index of the functional state of the primary motor cortex in seven patients suffering from Unverricht-Lundborg type (ULD) progressive myoclonus epilepsy (PME) and in seven healthy control subjects. In patients, the motor cortex rhythm was on average 5 Hz lower in frequency and its strength was double compared with controls. To study reactivity of the approximately 20-Hz rhythm, left and right median nerves were stimulated alternately at wrists. In controls, these stimuli elicited a small transient decrease, followed by a strong increase ("rebound") of the approximately 20-Hz level. In contrast, the patients showed no significant rebounds of the rhythm. As the approximately 20-Hz rebounds apparently reflect increased cortical inhibition, our results indicate that peripheral stimuli excite motor cortex for prolonged periods in patients with ULD.     

Genetic testing for Alzheimer''s disease: Impact on health behaviors

Cardiovascular disease is the leading cause of illness and death in the USA, as well as other countries. Advances in genetics have led researchers to identified associations between a number of cardiac syndromes and diagnostic molecular findings. Therefore, a more precise understanding of the molecular pathways involved in cardiovascular diseases is clinically significant. Current literature suggests that while etiologies remain complex, a number of cardiovascular diseases can be linked to specific metabolic inheritable factors. A broad multifactorial model is gradually being replaced with disease specific models where independent genetic and/or teratogenic pathways may lead to a particular outcome. These genetic pathways include chromosome deletions, disruptions (translocations), duplications of particular genetic regions, point mutations involving single genes, or alteration in the ability for a gene to be transcribed into a functional protein. In this review the molecular mechanisms underlying cardiovascular diseases and their clinical manifestations will be explained.     

Chronic Dementing Conditions, Genomics, and New Opportunities for Nursing Interventions

PURPOSE: To (a) provide an overview of chronic dementing conditions; (b) discuss the etiologic and clinical characteristics of Alzheimer disease (AD) and Parkinson disease (PD) within the framework of the family systems genetic illness model; and (c) to explore opportunities to enhance outcomes through the integration of genomics information and technologies into nursing practice. DESIGN: An integrated review of the literature, including the organizing construct of the family systems genetic illness model. FINDINGS: AD and PD are both influenced by genetic and environmental factors; in a small percentage of families, gene mutations are the primary etiologic factor. Genetic testing is an option for some families experiencing early-onset, familial disease. Presymptomatic and diagnostic genetic testing have limited clinical utility for the more common late-onset AD and PD. CONCLUSIONS: The current abilities of healthcare professionals to effectively intervene in people with AD and PD are limited by an incomplete understanding of the biologic basis of these diseases. Advances in genomics research and technology are providing the information and tools necessary to understand the molecular basis of these devastating disorders toward the goal of more specific and effective interventions.     

Digital karyotyping technology: exploring the cancer genome

Identifying gene-specific alterations in cancer genomes has revealed molecules that are causal effectors of carcinogenesis and specific targets for cancer molecular diagnosis and molecular-based cancer therapies. Whole-genome analyses of many cancer genomes at the resolution of single genes is thus a desirable yet incompletely realized goal that could expedite progress in cancer diagnosis and treatment. Although methods for routine whole-genome sequencing or high-resolution epigenetic measurements are currently under development, high-resolution measurements of gene copy number, or 'gene dosage', are now underway in several laboratories. Digital karyotyping, array comparative genomic hybridization, and single nucleotide polymorphism arrays are techniques that have the potential to detect gene amplification, homozygous deletion and loss of heterozygosity at or below the average length of single genes. Recently, digital karyotyping of a small number (<20) of colon and brain cancer genomes has revealed tumor cases with significant genetic dosage alterations affecting few and, in some cases, only one complete gene. These experiments suggest that gene-specific gene dosage alterations may be sufficiently frequent to enable the identification of promising tumor gene candidates in small-scale experiments. The purpose of this review is to describe our understanding of cancer as a genetic disease, review the basic principles, methodologies and interpretational issues of traditional and high-resolution whole-genome screens, and describe the potential of our first detailed look at whole cancer genomes for progress in the understanding and treatment of cancer.     

Care of chronic liver disease

Regardless of etiology, chronic liver disease generally involves a process of progressive destruction and regeneration of the liver parenchyma, leading to fibrosis and cirrhosis. At an early stage, most patients are asymptomatic and can easily go undiagnosed and untreated. Primary care physicians can often make the diagnosis but may offer little treatment. Better understanding about treatment is the key for primary care providers to provide better care for this group of patients. This review focuses on the treatment of the most common causes of chronic liver disease, including hepatitis B, hepatitis C, alcoholic cirrhosis, nonalcoholic fatty liver disease, and hemochromatosis.     

Some clinical implications of recombinant DNA technology with emphasis on prenatal diagnosis of hemoglobinopathies

Recombinant DNA technology has made possible remarkable advances in understanding the molecular genetics of human and other eucaryotic cells. This technology also has clinical applications, some of which may soon involve clinical laboratories. Restriction endonucleases and cloned DNA probes permit the direct analysis of cellular DNA to detect sequence abnormalities associated with particular genetic disorders. Use of this approach in the antenatal diagnosis of hemoglobinopathies is now possible on a routine basis. The principles behind the methods are quite general and may be applied to other hereditary diseases once suitable DNA probes become available. The same approach may be used to detect carriers of recessive gene defects and so improve genetic counselling. Other clinically related applications of recombinant DNA technology include the production of antigens for vaccine preparation and of specific human proteins (e.g. interferon and human growth hormone) for therapeutic use, as well as the use of nucleic acid hybridization for identification of microbial pathogens. It seems likely that recombinant DNA technology will, in the future, play an increasingly important role in the diagnosis, prevention and treatment of human disease.     

Hunting for fibrosis progression genes in hepatitis C patients

HCV (hepatitis C virus) represents one of the major health problems worldwide, as almost 170 million people are infected and most of these develop a chronic disease, often with the progression to cirrhosis and its complications. In the present issue of Clinical Science, Iwata and co-workers report an association between a variant of a gene regulating bile acid levels, ABCB11 1331T>C (where ABCB11 encodes ATP-binding cassette, subfamily B, member 11), and the progression to cirrhosis in patients with HCV, but not in fatty liver patients. They correlate this genetic variant with increased serum bile acid levels as a marker of cholestasis. These findings have important implications for researchers working to dissect the molecular mechanisms underlying liver fibrogenesis and disease progression; however, the implications for clinical hepatologists are less immediate.     

Rarely fast progressive memory loss diagnosed as Creutzfeldt-Jakob disease: A case report

BACKGROUNDCreutzfeldt-Jakob disease (CJD) is a rare degenerative disease of the central nervous system that can be contagious or hereditary and is a rare cause of rapidly progressive dementia. It almost always results in death within 1-2 years from symptom onset.CASE SUMMARYHere, we report the case of a 57-year-old male who initially experienced dizziness followed by a 1-mo fast decline in memory function. He presented to the local hospital and underwent magnetic resonance imaging and cerebrospinal fluid (CSF) examination, with no definitive diagnosis. However, the symptoms of progressive forgetting worsened. In addition, he exhibited progressive involuntary tremor of the limbs. Then, he came to our hospital, and according to the results of CSF examination, electroencephalography (EEG) and magnetic resonance imaging (MRI) tests and clinical manifestations of cerebellar ataxia, dementia, and myoclonus that rapidly progressed, with a short duration of illness, he was finally diagnosed with sporadic CJD (sCJD). CONCLUSIONThis case report aims to create awareness among physicians to emphasize auxiliary examination, CSF examination, EEG and MRI tests and recognition of cerebellar ataxia, dementia, and myoclonus that rapidly progress to prompt pursuit of an early diagnosis and identification of sCJD and to reduce complications.     

Recent advances in genetic testing for familial hypercholesterolemia

Introduction: Familial hypercholesterolemia (FH) is a common genetic cause of premature coronary heart disease that is widely underdiagnosed and undertreated. To improve the identification of FH and initiate timely and appropriate treatment strategies, genetic testing is becoming increasingly offered worldwide as a central part of diagnosis.

Areas covered: Recent advances have been propelled by an improved understanding of the genetic determinants of FH together with substantially reduced costs of appropriate screening strategies. Here we review the various methods available for obtaining a molecular diagnosis of FH, and highlight the particular advantages of targeted next-generation sequencing (NGS) platforms as the most robust approach. Furthermore, we note the importance of screening for copy number variants and common polymorphisms to aid in molecularly defining suspected FH cases.

Expert commentary: The need for genetic analysis of FH will increase, both for diagnosis and reimbursement of new therapies. An effective molecular diagnostic method must detect: 1) molecular and gene locus heterogeneity; 2) a wide range of mutation types; and 3) the polygenic component of FH. As availability of genetic testing for FH expands, standardization of variant curation, maintenance of clinical databases and registries, and wider health care provider education all assume greater importance.     

Exploring the biology of cancer of unknown primary: breakthroughs and drawbacks

Background

Cancer of unknown primary (CUP) ranks among the ten most common malignancies worldwide. Cancer of unknown primary presents as disseminated disease, has a dismal prognosis and remains a diagnosis of exclusion. The natural history and biology of the disease is poorly understood, and efforts are focused on identifying the specific ‘CUP signature’.

Materials and methods

We collected and analysed all published research in the biology of CUP from 1974 till present (Medline, Embase, ASCO and ESMO Congresses).

Results

Current scientific evidence suggests that aneuploidy and karyotype changes are frequent, while more subtle molecular aberrations, such as epidermal growth factor receptor family proteins, cKit/PDGFR are frequently overexpressed, although without prognostic significance. Loss of function of tumour suppressor genes, active angiogenesis, a hypoxic genetic programme and a mesenchymal transitory phenotype have been reported in CUP and may be indicative of unfavourable prognosis. Molecular pathway analyses have identified various biomolecules impacting on survival (pAKT, pMAPK, c‐Met, p21 and pPRS6). Finally, circulating tumour cells have recently been reported as a frequent phenomenon in CUP.

Conclusions

Overall, advances in understanding CUP biology have been weak and the application of gene expression profiling failed to identify an as yet elusive ‘CUP molecular signature’. MicroRNA, epigenetic and proteomic studies are warranted to better characterize the biological profile of CUP and unravel its mystery.     

A novel biallelic LMNB2 variant in a patient with progressive myoclonus epilepsy and ataxia: A case of laminopathy

The report of LMNB2‐related progressive myoclonus epilepsy and ataxia due to missense homozygous c.473G>T variant.     

DNA and RNA studies for molecular characterization of a gross deletion detected in homozygosity in the NH2-terminal region of the ATP7B gene in a Wilson disease patient

Wilson disease is an autosomal recessive disorder caused by defective function of the copper transporting protein ATP7B. Approximately 520 Wilson disease-causing mutations have been described to date. In this study we report the use of DNA and RNA analysis for molecular characterization of a gross deletion of the ATP7B gene detected in homozygosity in a Wilson disease patient. The c.51+384_1708-953del mutation spans an 8798?bp region of the ATP7B gene from exon 2 to intron 4. The results obtained suggest that the?combination of DNA and RNA analyses can be used for molecular characterization of gross ATP7B deletions, thus improving genetic counselling and diagnosis of Wilson disease. Moreover these studies, help to better establish the molecular mechanisms producing Wilson disease.     

Diagnosis of Wilson's disease: a comprehensive review

Wilson's disease is an autosomal recessive disorder of copper metabolism. The culprit gene is ATP7B. The worldwide prevalence is about 1 in 30,000, which may vary by population. Higher prevalence rates were reported using more sensitive screening techniques and pilot population screening. Typical presentations include neuropsychiatric and hepatic dysfunction, whereas atypical presentations are protean. Diagnosis relies on a high clinical suspicion, typical neurological symptoms, presence of Kayser-Fleischer rings, and reduced serum ceruloplasmin concentration. The conventional value of < 0.20 g/l is not a universal diagnostic value. Age of the subjects and analytical variations should be considered when interpreting these levels. Patients with inconclusive findings require further investigations such as 24 h urinary free-copper excretion, penicillamine challenge test, liver copper measurement, and detection of gene mutations. Direct molecular diagnosis remains the most decisive tool. Other tests such as non-ceruloplasmin-bound copper are unreliable. Potential pitfalls and limitations of these diagnostic markers are critically reviewed in this paper. The mainstays of therapy are trientine, penicillamine, and/or zinc. Liver transplantation is lifesaving for those with advanced disease. Ceruloplasmin oxidase activity and serum free-copper concentration should be monitored in patients on long-term de-coppering therapy to prevent iatrogenic copper deficiency.     

Science and technology in mitigating AIDS

The workshop emphasized contributions of genetic engineering in providing reagents and techniques for diagnosing and monitoring HIV infections. Despite a variety of tests for specific antibodies, virus antigens and nucleic acids no consistent serum profile has emerged that correlates well with virus life cycle or clinical course. HIV infections are a great deal more complex than hepatitis B infections where diagnosis and prognosis are very accurately based on serologic profiles. HIV generates at least 15 virus proteins all of which are immunogenic. The workshop emphasized studies on immunogenicity of the proteins. Full understanding of the virus life cycle and the clinical course of disease may require in-depth studies of the production and immunogenicity of the virus-directed catalytic and regulatory gene products. Fortunately, all of these reagents can be produced through biotechnology. The new techniques described in the workshop will allow expanded studies to proceed rapidly.     

The molecular genetics of rheumatoid arthritis disease gene

Rheumatoid arthritis(RA) is a chronic polyarthritis of unknown etiology affecting approximately 1% of the population worldwide. Previous studies have shown that the ratio of the risk for siblings of patients with the disease versus the prevalence of that disease in the general population (lambda s) is much greater in RA, suggesting that genetic factors may be involved in familial clustering. Using microsatellite marker analysis and sib-pair linkage study, we have identified three chromosome regions D1S214/253, D8S556 and DXS1232/984 as candidate loci for RA disease genes. In this article, we review the molecular genetic findings on the RA disease genes located respectively at each of the above chromosome regions. We show that the death receptor 3(DR3) gene, a Fas family member, containing nucleotide polymorphism is the candidate disease gene located at D1S214/253. We also identify the mutant forms of angiopoietin-1(Ang-1) and Dbl proto-oncogenes respectively as the candidate genes located at D8S556 and DXS1232/984. We surmise that these mutations are responsible for the impairment of apoptosis induction, angiogenesis and leukocyte function in the patients, which may predispose to autoimmunity.