WASHINGTON — The youngest daughter of Republican presidential candidate Rick Santorum, who suffers from a rare genetic disorder, has again been hospitalized, his campaign said Friday.

"Rick and his wife Karen have taken their daughter Bella to the hospital," spokesman Hogan Gidley said in a statement. "The family requests prayers and privacy as Bella works her way to recovery."

It was not immediately clear what prompted the hospital visit.

Santorum canceled a slew of campaign appearances in January when Isabella, or "Bella," was admitted to hospital with pneumonia just before Florida's key Republican primary.

The three-year-old has Trisomy 18, a rare and serious genetic disorder also known as Edwards syndrome that causes severe developmental disabilities and abnormalities. Most babies with the condition die before or during birth.

According to the US National Institutes of Health, only five to 10 percent of children with Trisomy 18 live past their first year.

Santorum frequently mentions his daughter when meeting voters on the campaign trail. He has six other children with his wife Karen, a neo-natal nurse. In 1996, their son Gabriel was born prematurely and died shortly after birth.

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Photo AFP/File, Paul J. Richards