Variable Phenotype in Three Siblings With RAN Binding Protein 2 Variant With Potential Preventive Treatment for...

Familial acute necrotizing encephalopathy, or acute necrotizing encephalopathy type 1 (ANE1), is a rare genetic disorder, with the majority of cases linked to a pathogenic variant in the RAN Binding Protein 2 (RANBP2) gene. Although it shares many features of the sporadic type, it shows significant phenotypic variability within the same family, with a tendency toward recurrence in many cases.

We report a case series of three siblings from a nonconsanguineous family, all carrying a pathogenic RANBP2 variant consistent with ANE1. Despite sharing the same genotype, the clinical spectrum was markedly variable.

A 40-month-old boy experienced multiple febrile seizures before presenting with influenza A-associated encephalopathy and a magnetic resonance imaging showing diffuse brain edema. His condition rapidly progressed to brain death despite intensive management.

A five-year-old girl had multiple episodes of febrile seizures and encephalopathy, with neuroimaging initially suggestive of acute disseminated encephalomyelitis. She responded well to corticosteroid therapy and remains neurologically stable with mild cognitive dysfunction at the last follow-up. Third case: A 39-month-old boy has remained neurologically intact despite recurrent viral infections and hospitalization. The surviving cases were given a preventive treatment plan with pulse steroids during influenza infections. At 2 years of follow-up, they still have no new episodes of encephalopathy.

This is the first report from Saudi Arabia on familial ANE with the common RANBP2 variant, with variable clinical, radiological, and outcome findings within the same family. Furthermore, pulse steroids during influenza infection may lower the risk of future encephalopathy attacks in patients with ANE1.