Hyperargininemia: 7-Month Follow-Up Under Sodium Benzoate Therapy in an Italian Child Presenting Progressive Spastic Paraparesis, Cognitive Decline, and Novel Mutation in ARG1 Gene

BackgroundHyperargininemia due to mutations in ARG1 gene is an autosomal recessive inborn error of metabolism caused by a defect in the final step of the urea cycle. Common clinical presentation is a variable association of progressive spastic paraparesis, epilepsy, and cognitive deficits.MethodsWe describe the clinical history of an Italian child presenting progressive spastic paraparesis, carrying a new homozygous missense mutation in the ARG1 gene. A detailed clinical, biochemical, and neurophysiological follow-up after 7 months of sodium benzoate therapy is reported.ResultsLaboratory findings, gait abnormalities, spastic paraparesis, and electroencephalographic and neurophysiological abnormalities remained quite stable over the follow-up. Conversely, a mild cognitive deterioration has been detected by means of the neuropsychologic assessment.ConclusionsFurther longitudinal studies by means of longer follow-up and using clinical, biochemical, radiological, and neurophysiological assessments are needed in such patients to describe natural history and monitor the effects of treatments.