Complex sentence: Adult polyglucosan body disease (APBD) is an orphan disease and a glycogen storage disorder that is caused by an inborn error of metabolism, caused by loss-of-function mutations in the "GBE1" gene that are inherited from both parents.
Split into simpler sentences: Adult polyglucosan body disease (APBD) is an orphan disease and a glycogen storage disorder that is caused by an inborn error of metabolism. Loss-of-function mutations in the "GBE1" gene that are inherited from both parents.