Diamond Blackfan anaemia: DBA; Diamond Blackfan anemia (US); Congenital Red Cell Aplasia

Diamond Blackfan anaemia is a rare disorder. It is usually identified in the first few months of life when a young child becomes severely anaemic. Some children, however, may not develop anaemia until later on in childhood. The anaemia is caused by a failure of the bone marrow to produce red blood cells ('red cell aplasia'). Some children with DBA may show physical features such as an extra thumb joint, cleft palate or a characteristic facial appearance. Many affected children are very short for their age, and may have delayed puberty. Children with DBA otherwise develop normally, and it is unusual for affected children to have learning difficulties.

DBA occurs in around 5 to 10 in 1,000,000 births. This means that each year in the UK there will be an average of seven babies born with DBA.

Infection with a particular virus (parvovirus) can cause a switch off of red blood cell production. Nearly always this lasts for such a short time that it goes unnoticed, but infection during pregnancy can sometimes cause severe anaemia in the baby. There is also a condition known as 'transient erythroblastopenia of childhood' in which red cell production is temporarily switched off, usually following a viral infection. This is rare in babies, being most common in toddlers and pre-school children. This gets better on its own within a few months, and can sometimes be difficult to tell apart from DBA, except by waiting to see if the anaemia improves on its own.

The diagnosis is easy if there is already an affected child within the family, or the baby has a physical feature of DBA. Otherwise, it is a matter of confirming that the problem lies in a red blood cell production failure, and then to exclude parvovirus infection. Preliminary blood tests will show if too few red blood cells are being produced. The next step is for a small sample of bone marrow to be taken, to confirm that the anaemia is caused by production failure. Tests on the marrow will also include checking for evidence of infection with parvovirus. There is an additional test which measures the level of an enzyme, adenosine deaminase (eADA), in the red blood cells. The eADA level is usually raised in DBA, and can provide further evidence that the anaemia is due to DBA. The red blood cells in DBA are often larger than average (they are said to have a 'high MCV'), which can give further support to a probable diagnosis of DBA.

The exact cause is not clear, but the problem seems to be a fault in one of the early steps of red blood cell production. In up to twenty-five per cent of affected children there is a fault within a gene called RPS19 (short for 'small ribosomal protein 19'). There is a lot of research looking for the genes that are damaged in the other seventy-five per cent, with some promising leads, but no definite answers as yet.

Rarely, some individuals will have a spontaneous remission, in which the red cell production switches back on, but this is uncommon, and is impossible to predict.

Treatment for DBA can be with medication (steroids), blood transfusion, bone marrow transplantation or use of cord blood which is a rich source of the bone marrow stem cells from an unaffected sibling identified prenatally. However, these options need to be discussed in detail with the child's specialist.

Inheritance patterns
In most cases DBA occurs sporadically. In subsequent generations the pattern of inheritance is typically autosomal dominant, although there may be variable severity within the family.

Prenatal diagnosis
Prenatal diagnosis is currently only possible if there is a mutation affecting RPS19, as DBA is usually clinically silent until early infancy.

UK DBA registry
The DBA Study Group, based at St George's Hospital, London SW17 0QT, has established a UK based registry of children with DBA to help learn more about the cause and treatment of this rare anaemia. For further information on the registry, please contact Dr Sarah Ball, Tel: 020 8725 3921.

Medical text written October 2003 by Dr S Ball, Consultant Paediatric Haematologist, St George's Hospital Medical School, London, UK.

DBA.UK

DBA.UK (Diamond Blackfan Anaemia Support Group)
71-73 Main Street
Palterton
Chesterfield S44 6UR
Tel: 0845 0941 548
e-mail: info@diamondblackfan.org.uk
Web: http://www.diamondblackfan.org.uk

The Group is a National Registered Charity No. 1083179, established in 1997. It offers support by telephone and letter and attempts to link families where possible. It publishes a newsletter twice a year and has information available, details on request. The Group is in touch with approximately 50 families.

Group details last updated March 2004.