Lacey Horwitch, 10, died early Tuesday morning after a bout with hemophagocytic lymphohistocytis and thyroid hormone resistance, the Northbrook Star reports.
Lacey was diagnosed with the rare disease in August 2011. HLH caused Lacey's immune system to attack her own organs and the cells that produce blood in her bone marrow.
After her diagnosis, community members rallied on her behalf, holding bone marrow registry drives in nearby towns and a dance event at Stevenson High School to benefit medical research.
Read more about Lacey in last year's Patch profile.