Mandibuloacral dysplasia progeroid syndrome patients have Metaxin 2 gene mutations that result in loss of Metaxin 2 protein expression, Metaxin 1 depletion, mitochondrial network fragmentation, and impaired apoptosis.171 A human SAM complex structure will advance understanding of how Metaxin 2 facilitates Metaxin 1 localization to the mitochondrial outer membrane. The gene discussed is MTX1; the disease is mandibuloacral dysplasia progeroid syndrome.