Dystrophin analyses for immunocytochemistry method: study of 517 cases

DYSTROPHIN ANALYSES FOR IMMUNOCYTOCHEMISTRY METHOD: STUDY OF 517 CASES (ABSTRACT)^*. THESIS. RIBEIRÃO PRETO, 1999.

ROSANA HERMINIA SCOLA^**

In 1987, the product of the Duchenne muscular dystrophy (DMD) gene was discovered and given the name of "dystrophin". From then on, the diseases marked by a deficiency or an absence of dystrophin have been called dystrophinopathies. DMD and Becker's muscular dystrophy (DMB) are the most commonly found dystrophinopathies, but the dystrophin deficiency also is observed in the Turner syndrome, in women with chromossome translocations presenting a DMD phenotype, carriers of DMD with cardiopathy and proximal weakness, myocardiopathy, certain forms of myalgias and cramps, as well in asyntomatic and high serum creatine kinase.

The purpose of this work was to study the specificity of immunolabelling of dystrophin through the immunocytochemistry method in dystrophinopathies and to determine the reliability of the test as compared to the other diagnostic methods, and to distinguish dystrophinopathies from other muscular diseases. A study was made of 517 cases, which had full clinical and laboratory diagnoses. These cases were grouped into several clinical and laboratory diagnoses prior to the performance of the dystrophin test. From these, the following were suggested: Dystrophinopathies, 227 cases; other muscular dystrophies, 150 cases; myotonic diseases, 16 cases; congenital myopathies, 33 cases; metabolic myopathies, 15 cases; inflammatory myopathies, 14 cases; neuromuscular junction diseases, 1case; lower motor neuron diseases, 37 cases; polyneuropathies, 5 cases; central nervous system diseases, 7 cases and miscellaneous, 11 cases.

All the 517 cases were immunolabelled with an antibody for carboxy terminal of dystrophin and classified again, in accordance with their immunolabelling pattern after this, we add 19 cases to the dystrophinopathies group (Duchenne muscular dystrophy 153 cases, Becker muscular dystrophy 68, outliners, Duchenne muscular in female, syntomatic carriers of Duchenne muscular dystrophy 7, possible carriers of Duchenne muscular dystrophy 9). In addition to the already know diseases classified as dystrophinopathies, others also showed a change in the immunolabelling pattern by dystrophin, such as congenital muscular dystrophy, facioscapulohumeral muscular dystrophy, distal myopathies, alpha-sarcoglycan deficiency, myotonic dystrophy, juvenile and infantile spine atrophy and congenital hypotonia from as unknown cause.

In 71 cases, immunolabelling was performed with antibodies for rod domain, amino and carboxy terminal of dystrophin. It was observed those cases with clinical and laboratory dystrophinopathy diagnoses, such as DMB, had failed to diagnose the diseases through immunolabelling with the use of the antibody for the carboxy terminal. After the used the amino terminal and rod domain the diagnosis was possible in all the cases. A pattern, which was proper to immunolabelling for congenital muscular dystrophy, was observed with use of the antibody for the carboxy terminal, which in most cases was also maintained when the other two antibodies were used.

In 48 cases of muscular dystrophies, a molecular assessment was conducted by using the polymerase chain reaction method (PCR), where it was also possible to detect the presence of deletions in the majority of the evaluated cases.

We arrived at the conclusion that dystrophin evaluation through the immunocytochemical method proved to be high sensitivity and specificity test in the group of the dystrophinopathies, being adequate for differentiating the cases which are suspected of being dystrophies of the limb girdle types. The greatest lack of agreement of dystrophin through immunofluorescence with the diagnosis was in the cases of congenital muscular dystrophy. It was possible to identify a specific immunocytochemical standard for congenital muscular dystrophy. In dystrophinopathies, immunolabelling is better for the diagnosis when compared to the fresh frozen sections processed muscular biopsy through histochemistry. The use of the three antibodies for different sites of dystrophin enables the sensitivity and specificity of the test to be increased. In the cases of DMD and DMB, we found a high frequency of deletions of the dystrophin genes. The major deletion sites in DMD and DMB were located between exons 3-19 and 42-52.

KEY WORDS: dystrophies, dystrophin, immunocytochemistry, PCR.

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*

Análise da distrofina pelo método de imunocitoquímica: estudo de 517 casos (Resumo). Tese de Doutorado, Faculdade de Medicina de Ribeirão Preto (Área: Neurologia). Orientador: Lineu Cesar Werneck.

Datas de Publicação

• Publicação nesta coleção
  06 Abr 2001
• Data do Fascículo
  Mar 2001