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Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) are caused by mutations in the DMD gene that encodes the cytoskeletal protein, dystrophin. Dystrophinopathies are inherited in an X-linked recessive manner. Due to the tremendous size of the gene (2.2 megabases), the DMD locus has a high spontaneous mutation rate, and one third of sporadic cases of DMD are due to a de novo mutation. There are seven tissue-specific promoters in the gene. The skeletal muscular transcript contains 79 exons and encode the full-length protein (427-kDa) located at the inner face of the sarcolemma of muscle fibers. DMD gene mutations are highly heterogeneous. Large rearrangements (deletions or duplications of one or more exons) are most frequently involved while point mutations account for 20 %-30 % of cases. A survey of current strategies of molecular diagnosis is presented here. In particular, the role of muscle biopsy (for dystrophin and RNA analyses) in the diagnosis of dystrophinopathies is discussed. In more than 90 % of cases, the clinical severity is correlated with the impact of the mutations on the reading frame and the expression of the dystrophin (absence or residual amount of mutated protein). Various mechanisms contribute to the exceptions. Besides the clinical interest for the patient, the identification of the mutation allows accurate genetic counseling in the familles, and is a necessary prerequisite for the inclusion of the patient in the genotype-based clinical trials.

14 p. ill. Les nouveaux traitements ‘sur mesure’ du cancer, qui ciblent des étapes très précises du processus tumoral, présentent certains avantages par rapport à la chimiothérapie classique et ‘aveugle’. Mais il y a une condition préalable : identifier les patients chez qui ils seront efficaces. C’est le rôle des tests appelés ‘diagnostics compagnons’. Le Centre du Cancer de l’Institut scientifique de Santé publique (ISP) et le Centre Fédéral d’Expertise des Soins de santé (KCE) ont examiné les panels de tests dits de Next Generation Sequencing, qui analysent plusieurs gènes à la fois, permettant une accélération dans la prise en charge des cancers. Si ces tests sont effectués dans un laboratoire central spécialisé qui en réalise un nombre suffisant, le remboursement de ces tests semble possible dans le budget actuel de l’INAMI. Mais la garantie et le contrôle de leur qualité reste la grande priorité. PRÉFACE 1 -- RÉSUMÉ 2 -- 1. INTRODUCTION 3 -- 1.1. CONTEXTE 3 -- 1.2. QUESTIONS DE RECHERCHE 3 -- 1.3. APPROCHE GENERALE 3 -- 2. PANELS DE GENES PAR NGS 4 -- 2.1. PHASES D’EXÉCUTION DES TESTS DE PANELS DE GÈNES PAR NGS 4 -- 2.2. DISPONIBILITE DES PANELS NGS 5 -- 2.3. AVANTAGES DES TESTS DE PANEL DE GENES PAR NGS POUR LE LABORATOIRE 7 -- 2.4. POINTS D‘ATTENTION 7 -- 2.5. REGLEMENTATIONS, ASSURANCE QUALITE ET FORMATION 8 -- 3. ASPECTS ÉCONOMIQUES 8 -- 3.1. IMPACT DE LA PRECISION DU TEST SUR LE RAPPORT COUT-EFFICACITE 9 -- 3.2. CODES DE FACTURATION ET BESOINS SNG POUR LA BELGIQUE 11 -- 4. INTRODUIRE DES TESTS DE PANEL DE GENES PAR NGS 12 -- RECOMMANDATIONS 13

Molecular diagnostics methods are not limited to specialized centers anymore. They play an important role for the diagnostic of infections commonly encountered in the clinical practice. Especially the detection of pathogens difficult to cultivate, such as viruses, has been greatly improved by these methods. Often, PCR has become the gold standard for the diagnostics of these pathogens. However, PCR cannot be used in any case, and it is not fail proof. Therefore, it is important to know when to use molecular methods and what are their strengths and weaknesses, in order to prescribe them rationally. This article reviews the characteristics of molecular tests and their main indications in the ambulatory setting.

The quick emerging of the several targeted therapies and the concept of personnalized medicine underlie the necessity to develop and to well organize a molecular biology (or molecular pathology) unit of high quality, dedicated to clinical care, in order to look for tissular and cellular theragnosis biomarkers. This new and sudden area of activity for a clinical pathologist is strongly linked to the knowledge of a new medical speciality in health care institutions. Thus, the molecular pathology (or molecular biology made from cellular or tissular samples) can nicely be implemented in a clinical pathology laboratory. This new mission for a pathologist has to be done in respect with a great quality assurance which should allow obtaining in a short-term an ISO 15189 accreditation to keep going to perform this activity. The present work aims to describe the main steps to be set up in the order to get an ISO 15189 accreditation in molecular pathology. The different chapters of this norm will not be described in their exhaustivity, but in their large lines. Finally, we will describe the potential difficulties and pitfalls to be avoided before getting this accreditation.

The advent of targeted therapies and personalized medicine in oncology has led in France to the settlement and organisation of a network of hospital molecular genetic platforms under the impetus of the National Cancer Institute (INCa). These platforms are, according to the concerned sites, integrated or not in pathology laboratories. The development of molecular biology methods, the choice of the procedures, the establishment of sample workflow, the quality control and the selection of the genomic alterations to be detected on each platform, have been left to the discretion of the different laboratories. Based on calls for project made by the INCa, hospital molecular genetic platforms were able to adapt their activity according to the assigned budgets. While the presence of some genomic alterations (i.e. KRAS gene mutations in metastatic colon adenocarcinoma or EGFR gene mutations in lung adenocarcinomas), may lead to administration of targeted therapies under the Marketing Authorization Application (MAA), others are associated with therapeutic clinical trials. However, increasing number of MAA for new molecules targeting genomic alterations is likely in the near future. In this context, it is necessary to quickly adapt the organisation of work of the hospital pathology laboratories performing molecular biology tests in order to meet the growing demand of oncologists in the field of targeted therapies. The purpose of this article is to describe the different steps of the settlement of a molecular genetic platform in an academic pathology laboratory (LPCE, CHU de Nice) and to show the experience of this laboratory specifically oriented on the support of the morphological and molecular diagnosis of lung cancer, thyroid cancer and malignant melanoma.

In this review, the authors emphasize the pivotal role of the pathology in the setting of a revolution which progressively transforms medical sciences into basic sciences. Several key aspects of this specialty will be discussed together with the main perspectives in the fields of oncologic disorders.

The recent discovery of the Janus Kinase 2 (JAK2(V617F)) mutation, an indicator of clonal expansion, has widely modified the diagnostic work-up of myeloproliferative disorders. However, histopathologic criteria of the WHO classification, focused on megakaryocytes abnormalities, have taken a central role in the diagnosis of essential thrombocytemia (ET), particularly to distinguish it from the prefibrotic myelofibrosis (PMF) evolving to a clinic myelofibrosis unlike true ET. The aim of our study is to evaluate inter-observer reproducibility and prognostic implications of these pathological criteria comparing diagnoses with clinical and biological follow-up.Forty-four patients presenting with isolated thrombocytemia were retrospectively evaluated. All patients were initially diagnosed with ET based on the PVSG classification from 1997. The initial bone marrow biopsy specimens were re-evaluated using the Thiele pathological classification: true ET, prefibrotic myelofibrosis (PMF) and early myelofibrosis. Patients were followed for a median of 6 years.Our population includes three patients with polycythemia vera and 41 patients with true ET. Based on clinical and biological follow-up, diagnoses were changed to idiopathic myelofibrosis in four of six patients with "early" myelofibrosis (66.7%), but in only one of 14 patients with PMF (7.15%). In contrast, the diagnosis of true ET was not changed in the 21 cases. Inter-observer reproducibility for pathological classification was 100%.In this study, our diagnostic methodology based on the clinico-biological follow-up, which has not been evaluated in previous studies, calls into question the diagnostic value of the pathological criteria in PMF.

The advent of the targeted cancer therapies administered to patients, according to the results of molecular biology techniques (in particular, in situ hybridization, "polymerase chain reaction" amplification and sequencing), has modified the practice of the surgical pathology laboratories. The necessity to answer to the needs of physicians for optimizing the medical care for patients who develop cancer has led to a policy of national debate, spurred by the National Institute of Cancer (INCa), in order to implement new procedures in the pathology laboratories. Thus, in addition to the structuring of molecular biology platforms and their labeling by INCa, the upstream control of the steps present between resection of tumor samples and molecular analysis has proved to be crucial. Indeed, the quality of this upstream time, called "pre-analytical" phase, determines the reliability of the molecular biology results and therefore the therapeutic strategy. We describe here the main steps to be checked in the pre-analytical phase. The optimization of this pre-analytical phase within the surgical pathology laboratory aims to reduce or render insignificant the risk of errors of molecular biology tests. These errors can indeed lead to false negative or false positive results whose therapeutic consequences can be particularly harmful to patients with cancer.