Clinical Characteristics Of Different Phenotypes In Children With Spinal Muscular Atrophy

Objective: To compare the clinical characteristics of spinal muscularatrophy (SMA) in children within different phenotypes.Methods: Totally66cases were enrolled in this study.Thecomparisons were performed in clinical manifestation, changes ofelectrophysiology, genetic test of homozygous deletions of survival motorneuron1gene (SMN1) and follow-up study. The statistics analysis wasdone by SPSS software for Windows.Results: All of66patients were characterized by symmetric muscleweakness and hypotonia, absence or decrease of deep tendon reflexes.39.4%of them were associated with atrophy.63.3%of SMAⅠpatientswere characterized by glossopharyngeal paralysis and30.3%byparadoxical breathing, while the rate ratios were much higher in those withfamily history（80.0%,50.0%）of which the age onset were younger (1stmonth). For patients type Ⅱand type Ⅲ, muscle fibrillation and deformitywere more common and functional abilities of some patients mightimproved naturally. EMG in73.3%of the patients suggested a motor neuron disease. There was no difference between3groups, age factorexcluded. Approximately90.5％of the patients in our cohort lacked bothcopies of SMN l. There was no significant difference in the deletionfrequency or subtypes among the3groups.Conclusions: Pulmonary cares are essential for SMA I with familyhistories in particular. Clinical manifestation of SMA Ⅱand SMA Ⅲ areof great heterogeneity for which a period of follow-up is necessary anddifferential diagnosis should pay more attention. Electrophysiology is animportant auxiliary examination. Genetic tests make a definite diagnosis.There is no significant difference in the deletion frequency among thesubtypes in electrophysiology and gene tests.