Major Loci on Chromosomes 8q and 3q Control Interferon γ Production Triggered by Bacillus Calmette-Guerin and 6-kDa Early Secretory Antigen Target, Respectively, in Various Populations.

Background: Interferon γ (IFN-γ) release assays (IGRAs) provide an in vitro measurement of antimycobacterial immunity that is widely used as a test for Mycobacterium tuberculosis infection. IGRA outcomes are highly heritable in various populations, but the nature of the involved genetic factors remains unknown.

Methods: We conducted a genome-wide linkage analysis of IGRA phenotypes in families from a tuberculosis household contact study in France and a replication study in families from South Africa to confirm the loci identified.

Tuberculin skin test negativity is under tight genetic control of chromosomal region 11p14-15 in settings with different tuberculosis endemicities.

A substantial proportion of subjects exposed to a contagious tuberculosis case display lack of tuberculin skin test (TST) reactivity. We previously mapped a major locus (TST1) controlling lack of TST reactivity in families from an area in South Africa where tuberculosis is hyperendemic. Here, we conducted a household tuberculosis contact study in a French area where the endemicity of tuberculosis is low.

Identification of a major locus, TNF1, that controls BCG-triggered tumor necrosis factor production by leukocytes in an area hyperendemic for tuberculosis.

Background: Tumor necrosis factor (TNF) is a key immune regulator of tuberculosis resistance, as exemplified by the highly increased risk of tuberculosis disease among individuals receiving TNF-blocker therapy.

Methods: We determined the extent of TNF production after stimulation with BCG or BCG plus interferon gamma (IFN-γ) using a whole blood assay in 392 children belonging to 135 nuclear families from an area hyperendemic for tuberculosis in South Africa. We conducted classical univariate and bivariate genome-wide linkage analysis of TNF production using the data from both stimulation protocols by means of an extension of the maximum-likelihood-binomial method for quantitative trait loci to multivariate analysis.