[Diagnostic difficulties in spinal muscular atrophy]

To describe the clinical findings of patients with spinal muscular atrophy (SMA) with survival motor neuron (SMN) gene deletion.

Descriptive study of SMA cases confirmed with the deletion of the SMN gene. Frequency determination of positive clinical and laboratory revised diagnostic criteria.

All of the 22 included patients had symmetrical muscle weakness, which was diffuse in those with onset of symptoms up to 6 months of age (75 %), and either proximal or predominant in lower limbs in the remaining group (67 %). Fasciculations and atrophy were both frequent findings (82 %). Laboratory tests findings were variable, with a positivity of 57 % for electrophysiology and of 58 % for muscle biopsy.

The presence of a deletion in the SMN gene can help to confirm this diagnosis in unclear presentations.