NHD is a rare intractable autosomal recessive leukodystrophy (Hakola, 1972) caused by genetic mutations of either DAP12 or TREM2 (Paloneva et al., 2002) and is considered as a type of “primary microgliopathy.” During the initial neurologic phase, usually in the third or fourth decade of life, patients develop personality changes and mild memory impairment. The gene discussed is TYROBP; the disease is Nasu-Hakola disease.