A common but mostly unknown disease has affected a well-known athlete, shedding light on the condition that afflicts four million Americans.

FOX's Colleen Cappon has details in today's "Housecall for Health":

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Tennis superstar Venus Williams' announcement Wednesday that she's withdrawing from the U.S. Open due to a medical condition known as Sjogrens Syndrome has shaken the sports world.

Sjogrens Syndrome affects four million people in the U.S., and affects moisture production glands in a person's body.  Side effects include dry mouth and eyes, joint pain and fatigue.  Experts describe the condition as life altering, not life threatening, but only time will tell if Williams will be able to return to tennis.

Housecall for Health, I'm Colleen Cappon, FOX News Radio.