Enigmatic femoral growth by loss of complement regulator CD59a

The paper “Deletion of the membrane complement inhibitor CD59a drives age and gender-dependent alterations to bone phenotype in mice” by Anja C. Bloom et al. in Bone 2016 (1) describes for the first time an increased femur length and cortical bone volume (with reduced mineral density) in male mice deficient in CD59a. It appears that the role of CD59a, which inhibits the assembly of the membrane attack complex (MAC) and thereby the terminal complement activation pathway (2), was rather underestimated in the past regarding bone tissue development and function.