RBCK1 and polyglucosan body myopathy: While AGBE has not been directly linked to iron homeostasis, a possible indirect link exists because mutations in RBCK1 (RanBP-type and C3HC4-type zinc finger-containing protein 1), a gene that encodes an E3 ubiquitin ligase, cause Polyglucosan Body Myopathy, a recently described glycogen storage disorder30.