Severe Combined Immune Deficiency

SCID is a collection of rare diseases, estimated to occur once in every 80,000 live births. If left untreated it always results in fatal infections within the first two years of life. At first, to prolong life, patients were placed in sterile isolators, away from direct human contact. This gave rise to the name "bubble babies." Currently bone marrow transplantation is available with varying degrees of success. Gene therapy to treat SCID is under development.

Although the first known description of SCID was in 1950, very little progress in understanding the genetic basis for the disease was made until the mid-1990s. SCID patients have a wide range of symptoms that make it difficult to define the number of genes involved. The development of strains of mice that exhibited SCID, either naturally or created by a laboratory technique called gene knockout, greatly enhanced the ability to study human SCID genes and permitted the development of strategies for treatment, such as bone marrow transplantation and gene therapy. Many SCID patients were able to live longer through bone marrow transplants. The study of these patients, combined with the advances from the Human Genome Project, has led to a rapid increase in our knowledge about the genetic cause of SCID. The genes involved in five different SCID diseases were confirmed in late 2001 and are described below.