LDB3 and cardiomyopathy: We hypothesized that PGM1-related cardiomyopathy arises from a glycosylation-independent disruption of Z-disk-mitochondrial coupling driven by loss of PGM1-LDB3 interactions, resulting in mitochondrial energy failure and impaired contractile function.<h4>Methods</h4>Induced pluripotent stem cell-derived cardiomyocytes (iCMs) were generated from PGM1-deficient patient fibroblasts.