Chronic Granulomatous Disease (CGD) is a rare inherited disorder in which patients suffer from severe infection and inflammation. The first indications of disease usually appear in early childhood. The basic defect has been found to be lie in specialised white blood cells called phagocytic cells, which are responsible for engulfing and destroying germs. In CGD, there is a defect in an enzyme (known as the NADPH-oxidase) that is responsible for generating bleach like substances that are important for killing some important germs. In one form of the disease known as p47 AR-CGD (which accounts for 30% of patients), there are defined mistakes in a gene called NCF1. This gene is needed to form a key component of NADPH-oxidase. In many cases, patients can be protected from infection by constant intake of antibiotics. However, in others potentially life-threatening infections break through. In some cases patients also develop serious inflammation requiring high doses of drugs such as steroids. CGD can be cured by bone marrow transplant and the best results are available when a matched sibling donor is available. Transplant from unmatched donors have a much worse outcome and as a result alternative treatments for patients without a matched donor are highly desirable. Gene therapy of p47 AR-CGD is performed by introducing a normal copy of the human NCF-1 gene into the blood forming stem cells in the patients' bone marrow by using a gene carrier (in this study called a lentiviral vector). After treatment of the bone marrow cells in a specialised laboratory they are given back to the patient and will grow into functional phagocytic cells. There have been no previous clinical trials for patients with p47 AR-CGD however there have been previous gene therapy clinical trials conducted in the UK for patients with the most common form of CGD, known as X-CGD.