Gene find is key to rare blood disease

MEDICAL RESEARCHERS have identified the gene responsible for a rare blood disorder and say the find could lead to an effective treatment for the incurable disease within the near future, writes Steve Connor.

Scientists can now test for the presence of mutations in the gene that result in the disease, which affects about 1 in every 50,000 babies. The discovery could soon lead to the possibility of replacing defective genes with healthy substitutes, a technique known as gene therapy.

Researchers from Guy's Hospital in London, with colleagues from the Karolinska Institute in Sweden, found the gene for agammaglobulinaemia - caused by a deficiency of white blood cells - by studying 33 families afflicted by the inherited disorder.

The disease usually affects males, with females being healthy carriers of the defective gene. Discovering the gene, and the mutations associated with the disease, has also shed light on how the deficiency of white blood cells comes about, according to the research, which is published in the latest issue of Nature.

The gene is responsible for the production of a substance involved in the communication of signals within cells in the body. A defect in it causes a block in the proliferation of white cells.

Sufferers are susceptible to infectious diseases. Affected children have to be given antibiotics and injections of antibodies, without which they would quickly die.

David Bentley, lecturer in molecular genetics at Guy's, said that it took about nine months to be sure the research team had found the right gene. The 'crucial evidence' came when mutations in the gene were found only in people suffering the disorder. 'We could design a test tomorrow for pre-natal screening,' he said, but it would not be introduced without genetic counselling.