SEATTLE — Apple CEO Steve Jobs is taking his second medical leave of absence in two years, raising serious questions about his health and the leadership of a company at the forefront of a personal computing revolution.

Apple did not provide any further information about Jobs’ current condition, including whether Jobs is acutely ill, whether the leave is related to his 2009 liver transplant or whether he is at home or in a hospital.

Apple spokesman Steve Dowling referred to the text of Jobs’ note to employees, which was made public today.

In the note, Jobs, 55, said he will continue as CEO and be involved in major decisions. As has been the case during past illnesses, Jobs said chief operating officer Tim Cook will be responsible for all day-to-day operations.

“I love Apple so much and hope to be back as soon as I can,” Jobs wrote. “In the meantime, my family and I would deeply appreciate respect for our privacy.”

U.S. stock markets were closed today for the Martin Luther King Jr. holiday. Apple’s shares plunged 6.4 percent in trading in Frankfurt.

By The Associated Press