Methaemoglobinaemia, Beta-Globin Type

What is methaemoglobinemia, beta-globin type?

Beta-globin type methaemoglobinemia is an inherited blood disorder that disrupts the function of haemoglobin, the molecule in red blood cells that delivers oxygen to cells in the body. Methaemoglobinemia is characterised by increased levels of an abnormal form of haemoglobin that is unable to deliver oxygen effectively.

In most individuals with beta-globin type methaemoglobinemia, the only symptom is cyanosis, a bluish tint of the skin, mucous membranes, or area underneath the fingernails due to a lack of oxygen in the blood. Symptoms may appear as early as 3 to 4 months of age. People with methaemoglobinemia do not improve when given additional oxygen because oxygen cannot bind to the defective haemoglobin.

How common is methaemoglobinemia, beta-globin type?

The incidence of beta-globin type methaemoglobinemia is unknown.

What genes are related to methaemoglobinemia, beta-globin type?

Mutations in the HBB gene cause methaemoglobinemia, beta-globin type.

The HBB gene produces one of the subunits of haemoglobin, called beta haemoglobin or the beta chain. Mutations in specific regions of the HBB gene lead to an abnormal version of beta haemoglobin known as haemoglobin M. haemoglobin M disrupts the normal interaction between iron and haemoglobin, which interferes with the delivery of oxygen to cells.

Other types of methaemoglobinemia can be caused by unusual reactions to certain drugs or chemicals, the shortage of a particular enzyme (called NADH-cytochrome b5 reductase), or by abnormal alpha-haemoglobin, the second type of protein found in haemoglobin.

How do people inherit methaemoglobinemia, 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.

What other names do people use for methaemoglobinemia, beta-globin type?

  • blue baby syndrome
  • congenital methaemoglobinemia
  • haemoglobin M disease

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