Nasu-Hakola Disease With Stroke-like Attack

Homozygous mutations in the triggering receptor expressed on myeloid cells 2 (TREM2) gene are known to cause Nasu-Hakola disease, which is a rare cause of progressive presenile dementia. A 36-year-old woman presented with repetitive seizures, a 5-year history of progressive behavioral and cognitive changes, and an affected sibling. Magnetic resonance imaging of the brain revealed an ischemic lesion in the left medial temporal lobe. Extensive evaluation of juvenile stroke revealed that viral and autoimmune encephalitides, serum lactate and pyruvate levels, and cerebrospinal fluid composition were all normal. Brain magnetic resonance imaging was notable of thinning of the corpus callosum and caudate and frontotemporal cortical atrophy, in addition to the ischemic lesion. Whole exome sequencing revealed a homozygous mutation (c.A257T; p.D86V) in TREM2. The present case expands the clinical phenotype of Nasu-Hakola disease and further suggests that TREM2 pathway might have role in vessel wall health.