MFN2 and Charcot-Marie-Tooth disease type 2A1: Given that complete knockout (KO) of MFN2 is embryonic lethal in mice and loss of function mutations in humans lead to the severe mitochondrial disease Charcot Marie Tooth Type 2A (CMT2A) [92], the heterozygous carriers of this variant as detected in centenarians may minimally reduce protein abundance or function.