Immunogenetics of Heparin-Induced Thrombocytopenia: Aim 2

Inclusion Criteria: 18 years of age or older; Ability to give informed consent; Participants with heparin/PF4 antibody and SRA testing for HIT, including:

participants with negative heparin/PF4 antibodies and negative SRA (controls), participants with positive heparin/PF4 antibodies and negative SRA(seroconversion cases), participants with positive heparin/PF4 antibodies and positive SRA (HIT cases); Treatment with unfractionated heparin or low molecular weight heparin (enoxaparin, dalteparin, tinzaparin) within 7 days of blood draw

Exclusion Criteria: Less than 18 years of age; Inability to give informed consent

There is no randomization involved in this study. Participants will be enrolled in equal numbers from three categories: (1) participants without HIT testing negative for heparin/PF4 antibodies (controls); (2) participants without HIT testing positive for heparin/PF4 antibodies (seroconversion cases); (3) participants with HIT testing positive for both heparin/PF4 antibodies (HIT cases).

Recruitment will be facilitated through collaborators in the Department of Medicine Hematology and through key study personnel in the VUMC Clinical Coagulation Laboratory. Patients with positive and negative heparin/PF4 antibody and serotonin release assay results will be identified in Clinical Coagulation Laboratory and the patient's provider will be approached about potential participation in research studies. If the potential participant is interested, they will be approached by study personnel for study description and possible consent. Alternatively, clinical collaborators from the Division of Hematology who are consulted and participating directly in a patients care may contact a potential participant directly for willingness to participate in the study.