MOLECULAR ANALYSIS AND ELECTROMYONEUROGRAPHIC ABNORMALITIES IN CROATIAN CHILDREN WITH PROXIMAL SPINAL MUSCULAR ATROPHIES

Childhood onset proximal spinal muscular atrophy presents with conside rable clinical variability. This study included 14 Croatian children a ged 11 days to 8 years with spinal muscular atrophy types I-III verifi ed clinically and electromyoneurographically. DNA of affected children was screened for deletions of exons 7 and 8 of the survival motor neu ron gene and for deletion of exon 5 of the neuronal apoptosis inhibito r protein gene. Motor nerve conduction velocity and compound muscle ac tion potential amplitude were decreased in children with spinal muscul ar atrophy type I and II. Deletions of exons 7 and 8 of the survival m otor neuron gene and of exon 5 of the neuronal apoptosis inhibitor pro tein gene in children with spinal muscular atrophy type I-II suggested existence of more genetic abnormalities as compared to type III. A de crease in compound muscle action potential amplitude and motor nerve c onduction velocity in children with spinal muscular atrophy correlated with the disease severity, probably as a result of axonal degeneratio n. Phenotypic severity in children onset spinal muscular atrophy is di rectly correlated with the extent of survival motor neuron and neurona l apoptosis inhibitor protein exon deletions.