The myocilin gene is the first glaucoma gene to be associated with primary open-angle glaucoma (POAG). The hereditary subset of POAG and the role of the myocilin gene in our population are not clearly defined. Identification of cases of hereditary glaucoma and a better appreciation of the role of the myocilin gene may allow earlier diagnosis of the disease and optimize management of those at risk for glaucoma.
Patients were recruited from university glaucoma practices in the Greater Toronto area from 1996 to 1998. Pedigree analysis and DNA banking were performed for each participant. Mutational analysis of the myocilin gene by means of single-strand conformation polymorphism analysis and direct sequencing was completed for 140 probands with POAG of diverse ethnic background.
A total of 103 patients (55.7%) had a family history of glaucoma. Disease-causing mutations of the myocilin gene were observed in 7 (5.0%) of the 140 probands, which accounted for 6.5% (5/77) of the familial cases. Most mutations were associated with familial disease, which implies a 50% risk of transmission of a high-risk factor for glaucoma.
The hereditary subset of POAG is significant, and heritable glaucoma should always be suspected. In spite of the diversity of the ethnic background of our subjects, the observed prevalence of myocilin gene mutations was comparable to that previously reported, and such mutations do not appear to spare any ethnic group.