Natalie Cole died on January 31 at the age of 65. Now a statement released by her family explains what killed the internationally renown singer.

Natalie Cole's family has revealed the singer's cause of death https://t.co/PS6aPzMxzY pic.twitter.com/s9nz0Yy6Y1

— Rolling Stone (@RollingStone) January 8, 2016

The official cause of death for Natalie Cole was idiopathic pulmonary arterial hypertension.

“This is a very serious and progressive disorder in which the small blood vessels of the lungs are markedly narrowed or obstructed,” the family’s statement read, adding that she was diagnosed with IPAH five years ago following her successful kidney transplant.

“She responded well to PAH-specific agents over many years, during which she performed many concerts worldwide,” the statement continued. “[She] eventually succumbed to intractable right heart failure, an outcome that unfortunately commonly occurs in this progressive disorder, despite modern therapies.”

Natalie Cole’s sisters, Timolin and Casey, spoke with Entertainment Tonight following their sister’s death, and expressed how grateful they were to have spent Christmas Eve together.

“We were very blessed and thankful to spend that very special day with her that she loved. It was her favorite time of year,” they said.

Legendary singer Smokey Robinson was concerned about Natalie Cole’s health in recent months.

“About nine months or so ago, we did a concert together in Arizona, and when I saw her that day she didn’t look good to me,” he told ET. “She lost a lot of weight and stuff, and I could tell because I had known her for so long and [we were] so close.”

Natalie Cole was the daughter of the late Nat King Cole. Her most famous recording was one done as a duet with her dad, although he had passed away many years prior.

Natalie Cole suffered from hepatitis C and had battled drug addiction in the past.

The music world will long mourn the passing of this amazing singer.