[Two cases of Werdnig-Hofmann disease]. / Enfermedad de Werdnig-Hofmann. Dos casos clínicos.

Spinal muscular atrophy (SMA) is an autonomic recessive disorder that affects the anterior horn cells of the spinal cord, degeneration of which results in proximal muscle weakness. It is classified into three types: I and II (Werdnig-Hoffmann disease) and III (Kugelberg-Welander disease). With an incidence of 1/10,000. We report two cases of infants with hypotonic syndrome, that were diagnose with SMA, in the first case by muscular biopsy, and in the second by electromyography and chromosomes study. It is import that the physicians know about this disease, and its complications.