Instead of traveling to Russia with the U.S. delegation, King will be with her mother Betty Moffitt, 91, and her brother Randy Moffitt, in Arizona. Former U.S. hockey player Caitlin Cahow, who was originally scheduled for the closing ceremony, will take King's place at the opening ceremony.
"It is important for me to be with my mother and my brother at this difficult time. I want to thank President Obama for including me in this historic mission and I look forward to supporting our athletes as they compete in Sochi," King said.
Obama selected the openly gay tennis legend for the delegation in December, along with Olympic figure skater Brian Boitano, who later came out, and Cahow. Their nominations were widely perceived as disapproval of Russia's anti-gay propaganda law.
"The President extends his thoughts and prayers to Ms. King and her family in this difficult time," The White House said in a statement.