Three variations of a human gene appear to impact human tuberculosis susceptibility, providing insight into why some patients infected with the Mycobacterium tuberculosis pathogen develop the full-blown disease and others do not.
The finding is published in the Proceedings of the National Academy of Sciences ( PNAS ).
Approximately one-third of the world's population is thought to be infected with the M. tuberculosis pathogen, yet only about 10 percent becomes ill with the active disease. Researchers suspect that a variety of factors interplay to determine who develops the full-blown disease.
Igor Kramnik and his colleagues at HSPH ( Harvard School of Public Health ) had previously identified a gene in mice called Ipr1 ( intracellular pathogen resistance 1 ) that plays a significant role in limiting the multiplication of intracellular pathogens M. tuberculosis and Listeria monocytogenes inside host cells.
The Adrian V.S. Hill team at Oxford University then examined the closest homolog of the mouse gene Ipr1 that can be found in humans a gene called SP110. Three variations of the SP110 gene were found to be associated with tuberculosis in humans.
The variations of SP110 emerged from an analysis of 20 pieces of genetic material called SNPs that were culled from an original set of 27 SNPs taken from samples provided by 219 families in The Gambia. Two of the variations and their association with tuberculosis were further replicated in samples from 99 families in the Republic of Guinea and 102 families in Guinea-Bissau.
Source: Harvard School of Public Health, 2006