The two types of available TB screening tests are: the TB skin test and TB blood test (interferon-gamma release assays or IGRAs); and the QuantiFERON®-TB Gold Plus (QFT-Plus, Qiagen, Germantown, MD, USA) and the T-SPOT®.TB test (T-Spot, Oxford Immunotec Ltd., Abingdon, UK). Here, IFNG is linked to tuberculosis.