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Beta-globin type methemoglobinemia is an inherited blood disorder. It disrupts the function of hemoglobin, the molecule in red blood cells that delivers oxygen to cells throughout the body. Methemoglobinemia is characterized by increased levels of an atypical form of hemoglobin that is unable to deliver oxygen efficiently.
In most individuals with beta-globin type methemoglobinemia, the only symptom is cyanosis, which is a bluish appearance of the skin, mucous membranes, or the area underneath the fingernails due to a lack of oxygen in the blood. Symptoms may appear as early as age 3 to 4 months. Methemoglobinemia symptoms do not improve when affected individuals are given additional oxygen, because oxygen cannot bind effectively to the abnormal hemoglobin.
The incidence of beta-globin type methemoglobinemia is unknown.
Mutations in the HBB gene cause methemoglobinemia, beta-globin type.
Hemoglobin consists of four protein subunits and four iron-containing molecules called heme. Heme molecules are necessary for red blood cells to pick up oxygen in the lungs and release oxygen to other cells in the body. Hemoglobin typically has two protein subunits call alpha-globin and two protein subunits called beta-globin. The HBB gene provides instructions for making beta-globin. Mutations in specific regions of the HBB gene lead to an atypical version of beta-globin known as hemoglobin M. Hemoglobin M interacts abnormally with heme molecules, which impairs the uptake of oxygen by red blood cells. As a result, a reduced amount of oxygen is delivered to cells throughout the body.
Other types of methemoglobinemia can be caused by abnormal alpha-globin, a shortage of a particular enzyme called NADH-cytochrome b5 reductase, or unusual reactions to certain drugs or chemicals.
Changes in this gene are associated with methemoglobinemia, beta-globin type.
This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.
These resources address the diagnosis or management of methemoglobinemia, beta-globin type, and may include treatment providers.
You might also find information on the diagnosis or management of methemoglobinemia, beta-globin type, in Educational resources (http://ghr.nlm.nih.gov/condition/methemoglobinemia-beta-globin-type/show/Educational+resources) and Patient support (http://ghr.nlm.nih.gov/condition/methemoglobinemia-beta-globin-type/show/Patient+support).
General information about the diagnosis (http://ghr.nlm.nih.gov/handbook/consult/diagnosis) and management (http://ghr.nlm.nih.gov/handbook/consult/treatment) of genetic conditions is available in the Handbook. Read more about genetic testing (http://ghr.nlm.nih.gov/handbook/testing), particularly the difference between clinical tests and research tests (http://ghr.nlm.nih.gov/handbook/testing/researchtesting).
To locate a healthcare provider, see How can I find a genetics professional in my area? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.
You may find the following resources about methemoglobinemia, beta-globin type, helpful. These materials are written for the general public.
You may also be interested in these resources, which are designed for healthcare professionals and researchers.
For more information about naming genetic conditions, see the Genetics Home Reference Condition Naming Guidelines (http://ghr.nlm.nih.gov/ConditionNameGuide) and How are genetic conditions and genes named? (http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/naming) in the Handbook.
Ask the Genetic and Rare Diseases Information Center (http://rarediseases.info.nih.gov/gard).
atypical ; autosomal ; autosomal dominant ; cell ; congenital ; cyanosis ; enzyme ; gene ; heme ; hemoglobin ; hemoglobin M ; incidence ; inherited ; iron ; molecule ; mucous ; oxygen ; protein ; symptom ; syndrome
You may find definitions for these and many other terms in the Genetics Home Reference Glossary (http://ghr.nlm.nih.gov/glossary).
The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.