Several other loci have been identified that modulate the disease course later on during the infection. It is possible that these mouse crosses have given researchers a genetic look at genes that influence the disease at different periods of infection. For example the chromosome 8 and 9 genes probably act before activation of the specific immune response and genes on other chromosomes may modulate the specific immune response. Finding glaucoma genes using a founder effect Glaucoma is one of the most common eye diseases - glaucoma causes pressure to build up inside the eyeball, which if untreated, causes blindness. Foote and Speed are trying to identify these genes, using a novel approach which takes advantage of 'the founder effect'.
Glaucoma occurs in Tasmania at the same frequency as elsewhere in Australia.
Tasmania is still a young population in genetic terms and records exist that allow genealogists to trace the descendants of many of the early colonists. This results in large extended family pedigrees which are like gold to geneticists. In collaboration with the Menzies Centre in Tasmania, the WEHI team is trying to identify every latter-day Tasmanian with glaucoma, and retrace their pedigrees back for six or seven generations, to identify patterns of inheritance for glaucoma. Such pedigrees have huge theoretical potential but Professor Speed and his colleagues need to develop new algorithms to use such pedigrees to identify the relevant genes. It is already clear that the most common form of glaucoma in Tasmanians is due to a dominant gene with incomplete penetrance - only a minority of those who inherit the mutant gene develop glaucoma.