Donald Burke is the father of Preston Burke.
He came with his wife to Seattle Grace Hospital to see his son while he was recovering from a gunshot wound. He and his wife walked in on Cristina Yang giving Burke a striptease. His reaction was shock. He had also brought flowers for Burke. Later, when he saw that Cristina was discouraged after Burke's mother didn't like her, he told her to hang in there.
He has one son, Preston. He doesn't seem to be as protective over his son as his wife. When Cristina became discouraged because Jane didn't like her, he told her to hang in there.