HAND2 and Tetralogy of Fallot: A number of patients have been reported with duplications and deletions of chromosome 4q33, the chromosomal region containing HAND2. Patients with both duplications and deletions have a high incidence of congenital heart defects including tetralogy of Fallot consistent with dosage sensitivity for this gene in human cardiogenesis but all duplications and deletions have affected multiple genes [29], [30].