[Long-term efficacy observation of nicotinamide in the treatment of early-onset progressive encephalopathy with brain edema and (or) leukoencephalopathy-2 caused by NAXD gene variation].

Abstract

Objective: To summarize the long-term efficacy of nicotinamide in treating pediatric early-onset progressive encephalopathy with brain edema and (or) leukoencephalopathy-2 (PEBEL2) caused by NAXD gene variation. Methods: This was a case report conducted from February 2019 to January 2025. The long-term efficacy of nicotinamide was observed by following up a child with PEBEL2 who received the treatment in the Department of Neurology, Beijing Children's Hospital Affiliated to Capital Medical University. The clinical data included changes in skin lesions, neurological symptoms. The modified Rankin scale (mRS) was used to evaluate the recovery of neurological function. Results: A boy was diagnosed with PEBEL2 caused by NAXD gene variation via genetic testing at Beijing Children's Hospital Affiliated to Capital Medical University in February 2019, when he was 4 years and 6 months of age. Immediately after diagnosis, nicotinamide treatment was initiated at an initial dose of 100 mg/d, which was increased by 100 mg per week and gradually increased to 500 mg/d; meanwhile, other therapeutic drugs were gradually discontinued. After 1 year and 8 months of treatment, the child's skin lesions had completely resolved; at the 2-year follow-up, dystonia in both upper limbs and swallowing dysfunction was alleviated significantly; by 2.5-year follow-up, his cognitive function also showed improvement. When the child was treated with 500 mg/d for 3 years, a rash appeared around the mouth. After the dose was reduced to 250 mg/d, the rash resolved, and the dose of 250 mg/d was maintained until the last follow-up. At the last follow-up in January 2025, the child was 10 years and 5 months of age. His mRS score decreased from 5 (before treatment) to 4. During the 6-year of continuous nicotinamide treatment, the child's condition remained stable without progression. Drug-related skin rashes occurred, but no severe drug-related adverse reactions were observed. Conclusions: PEBEL2 is a treatable mitochondrial disease. Nicotinamide treatment can effectively improve skin lesions and neurological symptoms in PEBEL2 patients, and the long-term administration demonstrates a favorable safety profile.