The daughter of Cubs first baseman Derrek Lee has a rare genetic disease that causes blindness in young children, and he said Friday he has started a foundation with the owner of the Celtics to find a cure. Jada, who is 3 years old and Lee's only child, has lost vision in one eye. Lee, the 2005 NL batting champion, has spent the last two weeks researching Leber's Congenital Amaurosis. He has teamed with Celtics owner Wyc Grousbeck, whose son is one of only about 3,000 people in the United States with the disease.