Merck Manual

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Overview of Hemoglobinopathies


Evan M. Braunstein

, MD, PhD, Johns Hopkins University School of Medicine

Last review/revision Jun 2022 | Modified Sep 2022
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Hemoglobinopathies are genetic disorders affecting the structure or production of the hemoglobin molecule.

Hemoglobin molecules consist of polypeptide chains whose chemical structure is genetically controlled. Different hemoglobins, as distinguished by electrophoretic mobility, are alphabetically designated in order of discovery (eg, A, B, C), although the first abnormal hemoglobin to be identified, sickle cell hemoglobin, was designated hemoglobin S.

Structurally different hemoglobins with the same electrophoretic mobility are named for the city or location in which they were discovered (eg, Hb S Memphis, Hb C Harlem). Standard description of a patient’s hemoglobin composition places the hemoglobin of greatest concentration first (eg, AS in sickle cell trait).

Some hemoglobinopathies result in anemias that are severe in patients who are homozygous but mild in those who are heterozygous. Some patients are compound heterozygotes for 2 different hemoglobinopathies and have anemia of varying severity.

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NOTE: This is the Professional Version. CONSUMERS: View Consumer Version
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