Hemoglobin made up of homotetramers of gamma globin chains. In alpha thalassemia, the underproduction of alpha globin chains stimulates the expression of gamma globin genes. As a result, gamma globin tetramers become predominant. In fetuses homozygous for deletions in alpha hemoglobin genes, the level of Bart's hemoglobin is 80%–100%, and hydrops fetalis (q.v.) results. The hemoglobin was identified at St. Bartholomew's Hospital in London. This venerable hospital, founded in 1123, is nicknamed “Bart's.” See hemoglobin fusion genes.
Subjects: Genetics and Genomics.