Acute severe encephalopathy related to human herpesvirus-6 infection in a patient with carnitine palmitoyltransferase 2 deficiency carrying thermolabile variants

We describe a male infant with carnitine palmitoyltransferase 2 (CPT2) deficiency who presented with acute encephalopathy related to human herpesvirus-6 (HHV-6) infection. He was hospitalized for pylexia and status epilepticus, diagnosed with acute encephalopathy, and treated with intensive supportive care including mechanical ventilation, support for hypothermia, and control of the intracranial pressure, that caused severe neurological sequelae. HHV-6 was detected in his cerebrospinal fluid, indicating HHV-6 related encephalopathy. In the acute phase, acylcarnitine analysis of blood suggested a defect of long chain fatty acid β-oxidation, and CPT2 deficiency was genetically confirmed. In addition, other gene alterations that have been previously reported as “thermolabile variants” were found. Some patients with the infantile form of CPT2 deficiency present with acute encephalopathy, but others do not develop encephalopathy. The correlation between phenotype and genotype has not been clarified. Our case may contribute to the elucidation of the genetic factor involved in acute encephalopathy in CPT2 deficiency.