Abdullah Morsy was in his mid-twenties and emerged as the spokesman for the family after his father was martyred in an Egyptian courtroom.
The youngest son of the late Egyptian president Mohamed Morsy passed away of a heart attack in a hospital in Giza, south of the capital Cairo.
Abdullah Morsy, who passed away on Wednesday, had accused security officials of being behind his father's death.
Abdullah Morsy was detained briefly late last year over conspiracy charges. He also spent a year in jail after the coup in 2015.
Mohammed Morsy, a member of the Muslim Brotherhood, was elected in Egypt's first-ever presidential election in 2012 after a popular uprising overthrew longtime leader Hosni Mubarak but was overthrown after a year into his rule by the Egyptian military in a coup led by his own defense minister, the tyrant Sisi.
ILKHA