BIOCHEMICAL AND IMMUNOCYTOCHEMICAL ANALYSIS IN CHRONIC PROXIMAL SPINAL MUSCULAR-ATROPHY

Immunocytochemical and biochemical analyses were carried out on patien ts affected by chronic SMA. Three groups of patients were identified. In group I, the muscle presented a fascicular atrophy; a high percenta ge of atrophic type II fibers; and fibers expressing fast, slow, embry onic, and fetal myosin isoforms. In group II, the muscle was character ized by atrophic fibers and normal/hypertrophic fibers expressing only slow myosin isoforms. In group III, the muscle was characterized by f iber type grouping and fibers coexpressing fast and slow myosin isofor ms but never embryonic or fetal MHC isoforms. The muscles of groups I and III contained both fast and slow myosins whereas group II muscles were predominantly slow by immunocytochemical analysis or only slow by biochemical analysis. In view of these results, immunocytochemical an d histochemical analyses could help to classify chronic SMA and help t o understand the different pathogenic processes which seem to be relat ed to the maturational stage of the muscle at the age of onset of the disease. (C) 1994 John Wiley and Sons, Inc.