Dish-Houston

Luci Baines Johnson, the youngest daughter of former President Lyndon Johnson, is being treated at the Mayo Clinic for what doctors suspect is a rare autoimmune disorder that affects the nervous system, her personal physician said Saturday.

Johnson, 62, who was flown by air ambulance to the clinic in Rochester, Minn., on Friday, remained in the neuro-intensive care unit, said Dr. Dudley Youman, her doctor in Austin and a family friend.

Initially, Johnson was admitted to a hospital in Austin, Texas, on Wednesday after experiencing "extreme weakness" in her arms and legs, Youman said.

Youman said Johnson had a mild viral illness preceding this, a sore throat and hoarseness that might have been some kind of warning sign.

"She had been in excellent health prior to that, with no medical issue of this type," said Youman, speaking by phone outside her hospital room, which was packed with family. "It was sudden onset."

Youman said he and other doctors suspect Guillain-Barre syndrome, which affects the nerves that control movement and can cause paralysis.

After running extensive tests at the Texas hospital earlier in the week, Youman said doctors decided it best to move her.

Testing continues, and Johnson is being closely watched and is undergoing immunoglobulin treatment for her presumptive diagnosis, her doctor said.

Family spokesman Tom Johnson, who is not related to Luci Johnson, said her husband, Ian Turpin; her four children, and her sister, Lynda Johnson Robb, were among those with her at the hospital.

Although the cause of Guillain-Barre syndrome is unknown, its sudden and unexpected onset can make it a devastating disorder, according to the National Institute of Health. Recovery is not quick.

Luci Baines Johnson is the founder of investment firm LBJ Wealth Management and vice president of BusinessSuites, a nationwide office business service center.

She serves on numerous boards including the LBJ Family Foundation, the Lady Bird Johnson Wildflower Center, the Lyndon Baines Johnson Foundation Board and the SafePlace Foundation Board.

She is a trustee emerita of Boston University, a life trustee of Children's Hospital Foundation of Central Texas and the Seton Fund. She is also a member of the advisory board of Trinity Episcopal School, and a former member of the advisory boards of The University of Texas, School of Nursing and the School of Communication.

"She's a very active person, socially, physically and mentally," Youman said. "This is just a dramatic change."

Johnson was the last person, before Chelsea Clinton, to go directly from the White House to college when she decided to attend the University of Texas in 1966. It was her impending wedding, however, that generated more media interest.