Osteoclasts [261] and bone marrow derived macrophages [149] from TREM2 deficient mice, and liver cancer [186] and glioma cell lines [183] in which TREM2 was knocked down had increased levels of caspase 3, Bcl-2-associated X protein (bax), Annexin V and TUNEL positivity, all suggesting that TREM2 deficiency enhanced apoptosis. The gene discussed is TREM2; the disease is central nervous system cancer.