The genetic studies on NHD suggest that this disorder is caused by a structural defect of two genes encoding different subunits of the same membrane receptor signalling complex, specifically the DNAX-activating protein 12 (DAP12, also named TYROBP) and the Triggering Receptor Expressed on Myeloid cell 2 (TREM 2) genes [7,8]. The gene discussed is TREM2; the disease is Nasu-Hakola disease.