Adenosine deaminase increased activity -ADA-

Acronym:

ADA

ORPHANET code:

99138

OMIM code:

102730

Group:

Red cell enzymopathies

Increased ADA activity (20 to 30 fold) is a very rare cause of congenital nonspherocytic haemolytic anaemia. This enzyme defect is transmitted as autosomal dominant trait. On the contrary, recessive hereditary deficiency of ADA is a cause of a severe combined immunodeficiency (SCID) without anaemia.

• What causes the disease and how common is it?

  This is a genetic disease leading to increased expression of the ADA gene, encoding the ADA enzyme. Most likely, mutations in or around this gene lead to an increased ADA activity in red blood cells. It has been described in only four unrelated families.

• What are the most frequent symptoms if I have the disease?

  In some patients with ADA increased activity the anaemia is associated with muscle weakness or cramping after exercise.

• Which treatment must I follow if I have the disease?

  Supportive measures such as red cell transfusions in case of severe anaemia. In some cases spleen removal (splenectomy) may improve the anaemia and thereby patient’s clinical situation.

• What is the risk of passing the condition on to my children?

  If one member of a couple has the mutated gene for ADA enzyme, there is a 50 percent risk of having a child affected by the disorder at each pregnancy. The risk of having a child who has not the disorder is also 50 percent at each pregnancy. Ask for genetic counselling to get a complete explanation.