Limb‐girdle muscular dystrophies (LGMD) are a group of genetically heterogeneous disorders characterized by predominantly proximal muscle weakness. We aimed to characterize epidemiological, clinical and molecular data of patients with autosomal recessive LGMD2/LGMD‐R in Brazil. A multicenter historical cohort study was performed at 13 centers, in which index cases and their affected relatives' data from consecutive families with genetic or pathological diagnosis of LGMD2/LGMD‐R were reviewed from July 2017 to August 2018. Survival curves to major handicap for LGMD2A/LGMD‐R1‐calpain3‐related, LGMD2B/LGMD‐R2‐dysferlin‐related and sarcoglycanopathies were built and progressions according to sex and genotype were estimated. In 370 patients (305 families) with LGMD2/LGMD‐R, most frequent subtypes were LGMD2A/LGMD‐R1‐calpain3‐related and LGMD2B/LGMD‐R2‐dysferlin‐related, each representing around 30% of families. Sarcoglycanopathies were the most frequent childhood‐onset subtype, representing 21% of families. Five percent of families had LGMD2G/LGMD‐R7‐telethonin‐related, an ultra‐rare subtype worldwide. Females with LGMD2B/LGMD‐R2‐dysferlin‐related had less severe progression to handicap than males and LGMD2A/LGMD‐R1‐calpain3‐related patients with truncating variants had earlier disease onset and more severe progression to handicap than patients without truncating variants. We have provided paramount epidemiological data of LGMD2/LGMD‐R in Brazil that might help on differential diagnosis, better patient care and guiding future collaborative clinical trials and natural history studies in the field.

Significant advances in the understanding and management of Duchenne muscular dystrophy (DMD) took place since international guidelines were published in 2010. Our objective was to provide an evidence-based national consensus statement for multidisciplinary care of DMD in Brazil. A combination of the Delphi technique with a systematic review of studies from 2010 to 2016 was employed to classify evidence levels and grade of recommendations. Our recommendations were divided in two parts. We present Part 1 here, where we describe the guideline methodology and overall disease concepts, and also provide recommendations on diagnosis, steroid therapy and new drug treatment perspectives for DMD. The main recommendations: 1) genetic testing in diagnostic suspicious cases should be the first line for diagnostic confirmation; 2) patients diagnosed with DMD should have steroids prescribed; 3) lack of published results for phase 3 clinical trials hinders, for now, the recommendation to use exon skipping or read-through agents.Keywords: muscular dystrophy, Duchenne; practice guideline; consensus; diagnosis; genetic testing; drug therapy; glucocorticoids; utrophin. RESUMOAvanços na compreensão e no manejo da distrofia muscular de Duchenne (DMD) ocorreram desde a publicação de diretrizes internacionais em 2010. Nosso objetivo foi elaborar um consenso nacional baseado em evidências de cuidado multidisciplinar dos pacientes com DMD no Brasil. Utilizamos a técnica de Delphi combinada com revisão sistemática da literatura de 2010 a 2016 classificando níveis de evidência e graus de recomendação. Nossas recomendações foram divididas em duas partes. Apresentamos aqui a parte 1, descrevendo a metodologia utilizada e conceitos gerais da doença, e fornecemos recomendações sobre diagnóstico, tratamento com corticosteroides e novas perspectivas de tratamentos medicamentosos. As principais recomendações: 1) testes genéticos deveriam ser a primeira linha para confirmação de casos suspeitos; 2) pacientes com diagnóstico de DMD devem receber corticosteroides; 3) por enquanto, a falta de publicações de resultados dos ensaios clínicos de fase 3, dificulta recomendações de uso medicamentos que "saltam exons" ou "passam" por código de parada prematura.

Limb girdle muscular dystrophies are heterogeneous autosomal hereditary neuromuscular disorders. They produce dystrophic changes on muscle biopsy and they are associated with mutations in several genes involved in muscular structure and function. Detailed clinical, laboratorial, imaging, diagnostic flowchart, photographs, tables, and illustrated diagrams are presented for the differential diagnosis of common autosomal recessive limb girdle muscular dystrophy subtypes diagnosed nowadays at one reference center in Brazil. Preoperative image studies guide muscle biopsy site selection. Muscle involvement image pattern differs depending on the limb girdle muscular dystrophy subtype. Muscle involvement is conspicuous at the posterior thigh in calpainopathy and fukutin-related proteinopathy; anterior thigh in sarcoglycanopathy; whole thigh in dysferlinopathy, and telethoninopathy. The precise differential diagnosis of limb girdle muscular dystrophies is important for genetic counseling, prognostic orientation, cardiac and respiratory management. Besides that, it may probably, in the future, provide specific genetic therapies for each subtype.Keywords: muscular dystrophies, ultrasonography, biopsy, magnetic resonance imaging, neuromuscular diseases. RESUMOAs distrofias musculares progressivas cintura-membros são desordens neuromusculares hereditárias autossômicas heterogêneas. Elas produzem alterações distróficas à biópsia muscular e estão associadas a mutações em diversos genes envolvidos na estrutura e função muscular. Fluxograma diagnóstico, fotos, tabelas e diagramas ilustrados dos aspectos clínicos, laboratoriais e de imagem são apresentados para o diagnóstico diferencial de distrofias musculares cintura-membros autossômicas recessivas comuns, diagnosticadas atualmente em um centro de referência no Brasil. Exames de imagem pré-operatórios direcionam o local da biópsia muscular. O padrão de envolvimento muscular difere de acordo com o subtipo de distrofia muscular cintura-membros. A substituição fibroadiposa do tecido muscular é mais acentuada no compartimento posterior da coxa na calpainopatia e proteinopatia relacionada à fukutina; anterior da coxa na sarcoglicanopatia; difusa na coxa na disferlinopatia e teletoninopatia. O diagnóstico diferencial preciso das distrofias musculares cintura-membros é importante para o aconselhamento genético, orientação prognóstica, tratamento cardíaco e respiratório. Além disso poderá, no futuro, provavelmente, propiciar terapias gênicas específicas para cada subtipo.Palavras-chave: distrofias musculares, ultrassonografia, biópsia, imagem por ressonância magnética, doenças neuromusculares.

Limb girdle muscular dystrophy type 2 G (LGMD2G) is caused by mutations in the telethonin gene. Only few families were described presenting this disease, and they are mainly Brazilians. Here, we identified one additional case carrying the same common c.157C > T mutation in the telethonin gene but with an atypical histopathological muscle pattern. In a female patient with a long duration of symptoms (46 years), muscle biopsy showed, in addition to telethonin deficiency, the presence of nemaline rods, type 1 fiber predominance, nuclear internalization, lobulated fibers, and mitochondrial paracrystalline inclusions. Her first clinical signs were identified at 8 years old, which include tiptoe walking, left lower limb deformity, and frequent falls. Ambulation loss occurred at 41 years old, and now, at 54 years old, she presented pelvic girdle atrophy, winging scapula, foot deformity with incapacity to perform ankle dorsiflexion, and absent tendon reflexes. The presence of nemaline bodies could be a secondary phenomenon, possibly associated with focal Z-line abnormalities of a long-standing disease. However, these new histopathological findings, characteristic of congenital myopathies, expand muscle phenotypic variability of telethoninopathy.

Coenzyme Q10 (CoQ10) deficiency is a clinically and genetically heterogeneous subtype of mitochondrial disease. We report two girls with ataxia and mitochondrial respiratory chain deficiency who were shown to have primary CoQ10 deficiency. Muscle histochemistry displayed signs of mitochondrial dysfunction—ragged red fibers, mitochondrial paracrystalline inclusions, and lipid deposits while biochemical analyses revealed complex II+III respiratory chain deficiencies. MRI brain demonstrated cerebral and cerebellar atrophy. Targeted molecular analysis identified a homozygous c.1015G>A, p.(Ala339Thr) COQ8A variant in subject 1, while subject 2 was found to harbor a single heterozygous c.1029_1030delinsCA variant predicting a p.Gln343_Val344delinsHisMet amino acid substitution. Subsequent investigations identified a large‐scale COQ8A deletion in trans to the c.1029_1030delinsCA allele. A skin biopsy facilitated cDNA studies that confirmed exon skipping in the fibroblast derived COQ8A mRNA transcript. This report expands the molecular genetic spectrum associated with COQ8A ‐related mitochondrial disease and highlights the importance of thorough investigation of candidate pathogenic variants to establish phase. Rapid diagnosis is of the utmost importance as patients may benefit from therapeutic CoQ10 supplementation.