Elvis Presley had a genetic heart defect that may have contributed to his premature death, a British documentary series reported, citing a DNA analysis of a sample of the singer's hair.

The producers of the documentary, airing Wednesday on Britain's Channel 4, said the sample of hair belonging to "The King of Rock and Roll" was purchased from a friend of his barber.

An analysis of Elvis's DNA identified a gene mutation known to cause hypertrophic cardiomyopathy, which causes thickening and weakening of the heart muscle.

Presley, who died August 8, 1977, at the age of 42, gorged on junk food and became addicted to drugs in the last years of his life.

His death has long been blamed on a drug overdose, but the coroner's report said he died from a heart attack.

Stephen Kingsmore, director of the Centre for Pediatric Genomic Medicine at Children's Mercy Hospital in Kansas City, performed the DNA analysis and concluded that the results provide "obvious evidence".

"We know that Elvis had a strong family history of heart failure, and we know that he died suddenly, and at autopsy his heart was indeed thickened, which is another word for cardiomyopathy of a particular type. So this was a very good fit with Elvis's clinical picture," Kingsmore told Channel 4's "Dead Famous DNA".

It is unfair to blame Presley's death on excessive eating and drug use because he had a "defect in his DNA," Kingsmore said.

"Dead Famous DNA" plans to air the results on upcoming shows of DNA analyses of other famous and infamous figures, such as Adolf Hitler, Marilyn Monroe and Britain's King George III.