Angela Castro, the eldest sister of Cuban revolutionary leaders Fidel and Raul Castro, has died following a long illness, another sibling who lives in exile confirmed Wednesday.

At 88, Angela was the first of the seven Castro brothers and sisters to die, and her passing served as another reminder of the looming mortality facing the entire clan. Fidel Castro, who stepped down in 2006, is 85; brother Raul, who took his place as president, is 80.

Angela's death was confirmed by Juanita Castro from her home in Miami. She told The Associated Press that her elder sister, known to close friends and relatives as "Angelita," had suffered from Alzheimer's for many years. Though her two older brothers became the most powerful men in Cuba, Angela led a quiet life out of the public eye. She was divorced, and is survived by five children, as well as grandchildren.

"She had been in a very delicate state for some time," Juanita Castro said, adding that her sister was cremated and her ashes taken to a farm in the eastern Cuban town of Biran where she was born. The farm has been turned into a museum.

She said her sister died at a clinic in Havana where she had been staying, and that she was unconscious and surrounded by her children when she died.

There was no confirmation of the death in Cuba's state-run media, and officials did not immediately respond to requests for comment. Both Fidel and Raul Castro have made a point of separating their personal and public lives, and seldom reveal intimate details that would be considered routine biography in many other countries.

Angela was the first of the seven children born to Angel Castro, a Spanish immigrant to Cuba and his second wife Lina Ruz. She was followed 18 months later by Ramon, who is now 87. Fidel Castro came next followed by Raul, Juanita, Emma and Agustina.

An official book about the Castros says Angela weighed a whopping 14 pounds when she was born, which locals blamed on the fact her mother had drunk wine during the pregnancy. Doctors told Lina to stay in bed for 40 days to recover, but she ignored them and returned quickly to her old routine.

Cubans interviewed in Havana on Wednesday hadn't heard about Angela's death, and most said they didn't even know who she was.

"I thought the oldest one was Ramon," said Nancy Lara, a 55-year-old housewife walking through Old Havana. She said the news inevitably made one contemplate the eventual passing of Fidel and Raul.

"It's hard to imagine, but I know it will be a very tough blow," she said.

Juanita Castro left Cuba in the 1960s, and has been estranged from Fidel and Raul for years. But she is said to have maintained close ties to Angela and her other siblings.

Angela had a fear of flying and so never left Cuba, Juanita said. She had been unable to walk in recent years, and found it difficult to speak on the phone because of the Alzheimer's.

Many of the most important participants in the 1959 revolution have died, including Vilma Espin, Raul's wife and a top official in her own right, and Celia Sanchez, a top rebel fighter and rumored lover of Fidel.

Argentina revolutionary icon Ernesto "Che" Guevara was killed in Bolivia in 1967. The last major revolutionary giant to pass was Juan Almeida, who fought alongside Fidel and later served as a Cuban vice president, in 2009.

Raul Castro, who has been spearheading market-based reforms of Cuba's Marxist economy, has said he hopes to save the country from an economic abyss in whatever time he has left.

Ann Louise Bardach, the author of several books about Cuba and the Castro family, said that even if Fidel and Raul maintain public silence about their sister's death, it is bound to have a great emotional impact on them.

"I'm sure that her passing, being the first born and the first to die, will resonate deeply with her brothers, for whom the bell tolls," she said.

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AP writer Gisela Salomon in Miami and Andrea Rodriguez in Havana contributed to this report.

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(This version CORRECTS sequence siblings were born).)