Autosomal dominant distal spinal muscular atrophy: an Italian family not linked to 12q24 and 7p14

Differential diagnosis of congenital muscular dystrophies

Congenital muscular dystrophies (CMDs) are defined by signs of muscle weakness in the first 6 months of life with myopathic changes in muscle biopsy. The progress in the last decade has helped to make molecular and genetic diagnoses in the majority of patients fulfilling these criteria. In a number of patients a definite diagnosis cannot be reached and these individuals are often grouped together as "merosin positive" congenital muscular dystrophy. In the last 5 years, 25 patients referred for assessment as possible congenital muscular dystrophy have been found to have alternative diagnoses. This paper aims to highlight these conditions as the common differentials or more difficult to diagnoses to consider in patients presenting as CMD.

Spinal muscular atrophy: clinical classification and disease heterogeneity

The clinical classification of spinal muscular atrophy, caused by deletion of the survival motor neuron 1 gene (SMN1), is based on age at onset and maximum function achieved. Evidence suggests that maximum function achieved is more closely related to life expectancy than age at onset. Therefore, it is important to wait for a period before assigning a patient to 1 of 5 classes of the disorder. Several diseases result from degeneration of the anterior horn cell but are not caused by SMN1. The classification for these conditions is evolving. This article offers an attempt at organizing one's thinking about this disease group.