PMPCB and cardiomyopathy: However, some disorders involve genes important for preprotein processing but do not present with cardiomyopathy, such as mutations in mitochondrial-processing peptidase subunit alpha (PMPCA) [140] and mitochondrial-processing peptidase subunit beta (PMPCB) [141], which encode subunits of MPP, and inner mitochondrial membrane peptidase subunit 2 (IMMP2L) which encodes a subunit of the mitochondrial inner membrane peptidase (IMP) [142].