RATIONALE: Acute necrotizing encephalopathy (ANE) is a specific type of 
encephalopathy usually followed by febrile infection. It has an aggressive 
clinical course; however, it usually does not recur after recovery in cases of 
spontaneous ANE. Nevertheless, there are several studies reporting recurrences 
in familial ANE with RAN-binding protein 2 (RANBP2) mutation. There are few 
cases of familial ANE with RANBP2 mutation in Asian populations.
PATIENTS CONCERNS: A 21-month-old Korean boy who was previously healthy, 
presented with seizure following parainfluenza - a virus and bocavirus 
infection, followed by 2 recurrent seizure episodes and encephalitis after 
febrile respiratory illnesses. Meanwhile, his 3-year-old sister had focal brain 
lesions on neuroimaging studies when evaluated for head trauma. The siblings 
also had an older brother who presented status epilepticus after febrile 
respiratory illness at the age of 10 months old.
DIAGNOSIS: Brain magnetic resonance imaging was performed to evaluate the 
seizure and neurologic symptoms. Imaging findings showed variable spectrum - 
from non-specific diffuse white matter injury pattern to typical "tricolor 
pattern" of the ANE on diffusion-weighted images. The other 2 siblings showed 
focal lesions in both external capsules and severe diffuse brain edema. Genetic 
tests identified a heterozygous missense mutation in the RANBP2 [c.1754C>T 
(p.Thr585Met)] in 2 siblings and their mother.
INTERVENTIONS: Patients were treated conservatively with anticonvulsive agents, 
intravascular immunoglobulin, and steroids.
OUTCOMES: Among the 3 siblings, 2 male siblings died from familial ANE, whereas 
the female sibling was asymptomatic.
LESSONS: These cases highlight the radiological aspects of familial ANE with 
incomplete penetrance of the RANBP2 gene in 3 family members, showing variable 
involvements of the brain and natural history on magnetic resonance images. 
Radiologists should be aware of the typical and atypical imaging findings of 
familial ANE for prompt management of affected patients.