A Case of Nasu-Hakola Disease without Fractures or Consanguinity Diagnosed Using Exome Sequencing and Treated with Sodium Valproate

Nasu-Hakola disease (NHD) is a rare autosomal recessive neuropsychiatric disorder characterized by bone cysts, fractures, and cognitive impairment. Two genes are responsible for the development of NHD; TYROBPand TREM2. Although it presents with typical signs and symptoms, diagnosing this disease remains difficult. This case report describes a male with NHD with no family or past history of bone fractures who was diagnosed using exome sequencing. His frontal lobe psychiatric symptoms recovered partially following treatment with sodium valproate, but not with an antipsychotic.