Myotonic dystrophy (DM) is a neuromuscular disorder caused by the expansion of the cytosine-thymine-guanine (CTG) repeat of the myotonic dystrophy protein kinase gene (DMPK). This repeat is highly polymorphic in healthy individuals [(CTG)5-37], and it has been proposed that expanded CTG alleles originated from larger sized normal alleles [(CTG)19-37]. According to this hypothesis, a positive correlation should be expected between the frequency of these large-sized normal alleles and the prevalence of the disorder in a population. We determined the distribution of CTG alleles of the DMPK gene in 156 healthy Brazilians from Rio de Janeiro city. Our analyses of 312 chromosomes detected 20 different alleles ranging in size from 5 to 27 CTG repeats, with 24 alleles having more than 18 repeats (7.69%). This frequency of (CTG)3(19) alleles observed in our population suggests that the prevalence of DM in Rio de Janeiro should not be different from the prevalence in European populations.

OBJETIVOS: Trabalho realizado em crianças com Distrofia Muscular tipo Duchenne (DMD), focalizando a atuação fisiátrica em razão da polêmica sobre os exercícios físicos nestes pacientes. Hoje, sabe-se que a DMD resulta de uma anomalia genética (Xp21) acompanhada da ausência de DISTROFINA, condição determinante da necrose do sarcolema e eliminação de sua propriedade contrátil durante as atividades físicas. MATERIAL E MÉTODOS: Foram atendidas 10 crianças DMD: 2 grabatárias e 8 com sinais conspícuos da doença. Todas receberam bloqueadores de cálcio, atenção cardiológica e respiratória. Excluiram-se os exercícios resistidos, de estiramento de estruturas retraídas e mobilizações passivas. Mantiveram-se: a órtese no momento de perda da deambulação, a assistência postural e a prevenção de fadiga. Mas, estabeleceu-se um programa domiciliar de atividades físicas escolar e recreativa moderadas, e exercícios de alongamento realizados de forma cautelosa. RESULTADOS E CONCLUSÃO: A exclusão da cinesioterapia e a restrição de atividades físicas extenuantes atenuaram a fadiga muscular e melhoraram a marcha, mantendo-se a capacidade física razoável em oito crianças. A atenção fisiátrica às crianças com DMD previne os encurtamentos tendinosos, melhora a qualidade de vida, presta assistência respiratória e orienta os familiares. Atualmente, muitos autores concordam sobre a vantagem da restrição de exercícios e da prevenção da fadiga muscular. Entretanto, aguardam-se mais esclarecimentos após a inclusão da cinesiologia nas pesquisas que estão em andamento.

The authors carried out a study of children with progressive muscular dystrophy of Duchenne type (DMD), giving special attention to physiatrical follow-up, having in mind that the practice of exercises has been debated very much in the specialized literature. The goal of this study is to try to settle the limits for the utilization of kinesitherapy which should be applied only in specific situations, such as: after skeletal muscular trauma or when the respiratory system is at risk. In this situation the physiatrical procedure would be to restrict physical activity, with early use of wheelchairs and the exclusion of the use of orthoses for orthostatism. DMD, at present, has been considered a result of duplication (60%), deletion (5 to 6%) or point mutations at gen Xp21 (Zatz, 1994), that codifies a protein called Dystrophin ( Hoffman et al., 1987). Dystrophin is a cytoskeletal sarcolemmic protein that constitutes about .002% of the total protein of the muscle, present in skeletal fibers concentrated in muscle tendinous joints, which supplies mechanical reinforcement to the surface of the membrane during stretching and shortening physical activity. This protein is absent in DMD cases, wherefore, the sarcolemma undergoes a segmentary necrosis losing its contractile property during eccentric and concentric physical activity. The importance of physiatrical follow-up for DMD patients is to avoid deformities and tendon shortening, to ameliorate the patient's quality of life, to provide respiratory assistance and general couseling to members of the patient's family. The objective of this study is to try to clarify the risks and possibilities of kinesitherapy applied to DMD cases.