American scientist Dr Stephen Kingsmore, who researched the death for a Channel 4 documentary, found mutations, or variants, which cause migraines, glaucoma and obesity after carrying out DNA analysis of a strand of Presley's hair.
Dubbed the king of rock 'n' roll, Presley was a junk food addict who relied heavily on prescription drugs. He was found dead at his Graceland home in 1977. He suffered from headaches, bad eyesight and ballooned in weight towards the end of his life.
But scientists also found a "crucial" DNA variant known to cause hypertrophic cardiomyopathy, a heart muscle disease which causes the thickening of the heart wall and weakening of the heart muscle itself.
Presley displayed many of the symptoms of this disease, including an irregular heartbeat, fatigue, fainting and high blood pressure.
Dr Kingsmore obtained the hair strand from the star's barber for the Channel 4 show. The programme controversially attempts to sequence the DNA of historical figures, from Adolf Hitler to Marilyn Monroe.
Producers of Dead Famous DNA said that although it was officially known Presley died of heart failure attack, the cause of his heart failure was still subject to speculation and had fuelled a "melting pot of conspiracy theories".
Dr Kingsmore, director of the Centre for Paediatric Genomic Medicine at the Children's Mercy Hospital in Kansas City, described the results as a smoking gun.
He said the results indicate it could be unfair to blame the singer's lifestyle for his death. Dr Kingsmore said: "There has been so much speculation about cause of death, and so much ill spoken of his lifestyle, and we had this intriguing finding that possibly Elvis had a medical illness, and all of the stuff about how he killed himself with his lifestyle might have been very unfair."
Presenter Mark Evans said they were "very, very confident" that the sample of hair had come from the singer, after spending three years doing their research.
"I'm massively confident that it is Elvis's DNA but I can't prove it," he said. "I can't tell you 100% that is Elvis' DNA. That's not possible."
The show also attempts to examine the DNA of Charles Darwin and King George III, from a hair sample from a wig, and, most controversially, Hitler.
Producers would not confirm whether a bone sample, said to be from Hitler's ribcage, turned out to be genuine and defended the decision to seek his DNA.
Results of scientific testing on the bone, which was given to the show's presenter by an unidentified man, will be revealed in later episodes.