It is a mutation in a gene that causes the eye disease glaucoma, according to collaborative research conducted by Swedish, Tunisian, and American researchers. The findings were recently published in the journal Nature Genetics.

The most common form of glaucoma, so-called open-angle glaucoma, is a disease that afflicts more than 16 million people in the world. The nerve fiber layer of the optic nerve slowly withers, leading to a deterioration of wide-angle vision and ultimately to serious vision impairment.

It was previously believed that glaucoma is caused by elevated pressure in the eye. But now Peter Söderkvist and Mounira Hmani-Aifa at the Faculty of Health Sciences, Linköping University, Sweden, in collaboration with Tunisian and American researchers, have managed to identify the pathogenic gene PRSS56, which is a serine protease. However, it remains unclear which protein(s) is the substrate for PRSS56.

The scientists studied Tunisian families who have been afflicted with both glaucoma and microphthalmia, diminished eyeballs, and in this work they managed to identify the gene that is mutated and causes the disease. The American research team participating in this collaboration identified an altered version of the gene in a mutagenesis screen in mice, selected for glaucoma.

The findings were achieved as part of a bilateral collaboration project between the Center for Biotechnology in Sfax, Tunisia and the Faculty of Health Sciences at Linköping University, a project that specifically targets research on families with genetic disorders. The project is funded by the Swedish Research Council and SIDA, the Swedish Development Cooperation Agency.