The first family consisted of two siblings affected by NHD and homozygous for the TREM2 p.Q33X mutation (referred to as NHD1 and NHD2) and a third sibling who is homozygous for TREM2 WT (referred to as SB CTRL; Fig. 1a, c and Supplementary Table 1, online resource). The gene discussed is TREM2; the disease is Nasu-Hakola disease.