title: New variants, challenges and pitfalls in DMD genotyping: implications in diagnosis, prognosis and therapy.
abstract: Molecular characterization of patients with Duchenne or Becker muscular dystrophies is essential for establishing a differential diagnosis, allowing appropriate clinical follow-up, patient management and genetic counseling. In light of the recent mutation-based therapeutic approaches, DMD gene analysis has gained further relevance. Owing to the size and complexity of the DMD gene and the diversity of mutation types, molecular analysis is not always a straightforward task requiring the combination of several methodologies. Our national genetic diagnostic service genetically characterized 308 dystrophinopathy patients (284 unrelated families), leading to the identification of 175 distinct mutations, including 39 unpublished variants. These studies revealed several potential diagnostic pitfalls (because of technical limitations or related with DMD's genetic heterogeneity) that may be overlooked even considering the international disease-specific diagnostic guidelines. Comprehensive analysis involved expression studies at the mRNA level, the identification of splicing changes and ultimately providing evidence for apparent exceptions to the reading-frame rule. Besides increasing the mutation detection rate, this detailed molecular characterization is indispensable for the identification of suitable candidates for the new mutation-centered therapies. As patient registries are internationally recognized as essential for clinical trial recruitment, this led us to develop the Portuguese Duchenne and Becker Muscular Dystrophy registry in collaboration with the Translational Research in Europe-Assessment and Treatment of Neuromuscular Diseases network.
authors.affiliation: 1] Unidade de Genética Molecular, Centro de Genética Médica Dr. Jacinto de Magalhães, Centro Hospitalar do Porto, Porto, Portugal [2] Departamento de Ciências Biológicas, Laboratório de Bioquímica, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal.
authors.forename: Rosário
authors.initials: R
authors.lastname: Santos
authors.affiliation: Unidade de Genética Molecular, Centro de Genética Médica Dr. Jacinto de Magalhães, Centro Hospitalar do Porto, Porto, Portugal.
authors.forename: Ana
authors.initials: A
authors.lastname: Gonçalves
authors.affiliation: Unidade de Genética Molecular, Centro de Genética Médica Dr. Jacinto de Magalhães, Centro Hospitalar do Porto, Porto, Portugal.
authors.forename: Jorge
authors.initials: J
authors.lastname: Oliveira
authors.affiliation: Unidade de Genética Molecular, Centro de Genética Médica Dr. Jacinto de Magalhães, Centro Hospitalar do Porto, Porto, Portugal.
authors.forename: Emília
authors.initials: E
authors.lastname: Vieira
authors.affiliation: Consulta de Neurologia Pediátrica, Hospital D. Estefânia, Centro Hospitalar Lisboa Centro, Lisboa, Portugal.
authors.forename: José Pedro
authors.initials: JP
authors.lastname: Vieira
authors.affiliation: Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK.
authors.forename: Teresinha
authors.initials: T
authors.lastname: Evangelista
authors.affiliation: Unidade de Neuropediatria, Hospital de Santa Maria, Centro Hospitalar Lisboa Norte, Lisboa, Portugal.
authors.forename: Teresa
authors.initials: T
authors.lastname: Moreno
authors.affiliation: Consulta de Doenças Neuromusculares, Serviço de Neuropediatria, Centro Hospitalar do Porto, Portugal.
authors.forename: Manuela
authors.initials: M
authors.lastname: Santos
authors.affiliation: Centro de Desenvolvimento da Criança Luís Borges, Hospital Pediátrico de Coimbra, Centro Hospitalar de Coimbra, Coimbra, Portugal.
authors.forename: Isabel
authors.initials: I
authors.lastname: Fineza
authors.affiliation: 1] Departamento de Ciências Biológicas, Laboratório de Bioquímica, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal [2] Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.
authors.forename: Elsa
authors.initials: E
authors.lastname: Bronze-da-Rocha
mesh_terms: D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D019295:Computational Biology; D018076:DNA, Complementary / Q000235:genetics; D003937:Diagnosis, Differential; D016189:Dystrophin / Q000235:genetics*; D005060:Europe; D005260:Female; D005838:Genotype; D006801:Humans; D007223:Infant; D008297:Male; D020388:Muscular Dystrophy, Duchenne / Q000175:diagnosis / Q000235:genetics* / Q000628:therapy; D009154:Mutation; D011174:Portugal; D011379:Prognosis; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics; D016364:Reading Frames; D012042:Registries
chemical_list: D018076:DNA, Complementary; D016189:Dystrophin; D012333:RNA, Messenger