Hyperargininemia: a family with a novel mutation in an unexpected site.

Hyperargininemia is a rare autosomal recessive disorder of the last step of the urea cycle characterized by a deficiency in liver arginase1. Clinically, it differs from other urea cycle defects by a progressive paraparesis of the lower limbs (spasticity and contractures) with hyperreflexia, neurodevelopmental delay and regression in early childhood. Growth is affected as well. Hyperammonemia is episodic, if present at all. The disease is caused by mutations in the ARG1 gene; there are approximately 20 different known ARG1 mutations with considerable genetic heterogeneity. We describe two Arab siblings with a late diagnosis of hyperargininemia and present the genetic findings in their family. As ARG1 sequencing was unrevealing despite suggestive clinical and laboratory findings, molecular cDNA analysis was performed. The ARG1 expression pattern identified a 125-bp out-of-frame insertion between exons 3 and 4, leading to the addition of 41 amino acids and a premature termination codon TGA at the sixth codon downstream. The insertion originated at intron 3 and was attributable to a novel c.305 + 1323 t > c intronic base change that enabled an enhancement phenomenon. This is the first reported exon-splicing-enhancer mutation in patients with hyperargininemia. The clinical course and genetic findings emphasize the possibility that hyperargininemia causes neurological deterioration in children and the importance of analyzing the expression pattern of the candidate gene when sequencing at the DNA level is unrevealing.

Multicenter long-term follow-up of children with idiopathic West syndrome: ACTH versus vigabatrin.

BACKGROUND AND PURPOSE: Long-term follow-up of children with idiopathic West syndrome (WS) treated with adrenocorticotropic hormone (ACTH) or vigabatrin. METHODS: Records of 28 normal magnetic resonance imaging (MRI) WS cases were reviewed for seizure development and cognitive outcome in relation to treatment type and lag. RESULTS: Average age at disease onset was 5.5 months, and average lag time to treatment was 25 days. Fourteen patients were treated with ACTH (eight early and six late), and 14 with vigabatrin (without delay). Response rates were 88% for ACTH and 80% for vigabatrin. Short-term outcomes for seizure cessation and electroencephalography normalization were identical between the groups. In the long-term, early ACTH treatment was better than the rest combined. Average follow-up time was 9 years. A normal cognitive outcome was achieved in 100% of the early-ACTH group, 67% of the late-ACTH group and 54% of the vigabatrin group (P = 0.03). Seizures subsequently developed in 54% of the vigabatrin group, in 33% of the late ACTH group, and 0% of the early ACTH group (P < 0.05). CONCLUSIONS: Idiopathic WS with normal MRI is associated with a good cognitive outcome. Early ACTH treatment, administered within 1 month, yields a better cognitive and seizure outcome than vigabatrin or late ACTH.