In 2008, Carlos Slim Domit watched his younger brother suffer progressive health troubles. Not yet 40, Patrick, chairman of Latin America’s largest wireless company, was often fatigued, his hands and feet swollen.

After doctors told Patrick his kidneys were beginning to fail, Carlos had himself tested to see if one of his could be used to save his brother. So did his father, the Mexican billionaire Carlos Slim. The younger Carlos turned out to be the best fit, and surgeons transplanted his kidney to Patrick.

“I wouldn’t have imagined how immediate the change would be,” Carlos said in an interview. “He had better color. He had another expression.”

The Slim family, led by the world’s richest man, has taken the experience as a call to action in their native Mexico. While the country’s rate of organ donation is one of the lowest in Latin America, the family is using its wealth and public profile to encourage people to embrace the practice.

The brothers Carlos and Patrick have unveiled a campaign with the country’s Health Ministry to promote organ donation. Through print and television advertising, the effort will explain the need for donations and encourage Mexicans to talk with loved ones about contributing their bodies after death.

“I urge you to allow, when you die, that your organs be taken to give life and quality of life to others,” Patrick said Friday at a news conference in Mexico City.

The younger Carlos said Mexicans may grow more comfortable with the idea of organ donations by hearing the brothers’ story.

“Learning and hearing about the experience from people who have been through the process can always help,” said Carlos, 43, the eldest of the six children of Carlos Slim and chairman of Telefonos de Mexico SAB.

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