Understanding hemophilia A and immune responses across families

HARP is a long-term research study that follows families with hemophilia A—a bleeding disorder caused by low levels of a protein called factor VIII. Researchers want to understand why some people develop immune responses (called inhibitors) to factor VIII treatment and what factors affect bleeding risk, starting before a baby is even born. By tracking mothers during pregnancy and their children through early childhood, along with other family members, this study aims to uncover the genetic and environmental factors that influence how hemophilia A develops and how the body reacts to treatment.

Hemophilia A is a serious inherited bleeding disorder, and one major complication is when patients develop inhibitors—immune responses that make factor VIII treatment less effective. Pregnant people with hemophilia are also at high risk for dangerous bleeding after delivery. This study exists to identify the genetic and other factors that influence these outcomes so doctors can better predict risks and improve care for families affected by hemophilia A.