Transient neonatal cyanosis is a rare inherited fetal hemoglobinopathy caused by mutations in the gamma-globin gene, HBG2. Clinical clues include reduced hemoglobin oxygen saturation without arterial hypoxemia. Fetal hemoglobin (HbF) is composed of two alpha and two gamma chains. Postnatally, globin expression shifts from gamma to beta, producing adult hemoglobin (HbA), composed of two alpha and two beta chains. Thus, symptoms gradually abate in the first months of life.
