Actress Angelina Jolie poses for a photograph as she arrives for the G8 Foreign Ministers Meeting in central London in this April 11, 2013 file photo.[Photo/Agencies]

Related: Angelina Jolie has double mastectomy to elude cancer

Debbie Martin, the younger sister of Jolie's mother, died at age 61 at Palomar Medical Center in Escondido, near San Diego.

Her husband, Ron Martin, told Britain's Sky News that his wife had the same defective BRCA1 gene as Jolie.

Jolie's mother, Marcheline Bertrand, died of breast cancer in 2007 at age 56.

On May 14, Jolie, the Oscar-winning film star, revealed she had a double mastectomy in an article in the New York Times, saying she hoped her story would inspire other women fighting the life-threatening disease.

Jolie, 37, is raising a family with fellow actor and fiance Brad Pitt. She wrote that she went through with the operation in part to reassure her six children that she would not die young from cancer, as her own mother did.

"We often speak of 'Mommy's mommy,' and I find myself trying to explain the illness that took her away from us. They have asked if the same could happen to me," wrote Jolie.

"I have always told them not to worry, but the truth is I carry a 'faulty' gene."

The actress, who won an Oscar as best supporting actress for her 1999 role in the film "Girl, Interrupted," said she opted for the surgery after her doctors had estimated she had an 87 percent risk of breast cancer and 50 percent risk of ovarian cancer, due to an inherited genetic mutation.