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Mutations in the myocilin gene in families with primary open-angle glaucoma and juvenile open-angle glaucoma
Mirella Bruttini1, Ilaria Longo, Paolo Frezzotti
1Division of Medical Genetics, Department of Molecular Biology, University of Siena, Siena, Italy.
Objectives:
To investigate the prevalence of myocilin (MYOC) mutations in Italian families with glaucoma and to determine the relationship of these mutations to primary open-angle glaucoma (POAG), juvenile open-angle glaucoma (JOAG), and pigmentary dispersion glaucoma.
Methods:
Twenty-six patients with POAG were selected based on a positive family history of glaucoma. All patients and 210 relatives had an accurate clinical characterization.
Main Outcome Measure:
Each index patient was screened by single-stranded conformational polymorphism analysis for mutations in the MYOC gene.
Results:
A MYOC gene mutation was found in 2 families. In one family, a previously reported p.K423E mutation was transmitted from the index patient with POAG to the 2 sons with JOAG. In the second family, a p.C25R change, affecting the signal peptide, was transmitted from the index patient with POAG to the son with JOAG, but not to the son with pigmentary dispersion glaucoma.
Conclusions:
Clinical characterization of 2 families with MYOC gene mutations indicates that POAG and JOAG are the 2 sides of a continuum phenotypical spectrum due to a common molecular defect. On the other hand, our results confirm the different origin of pigmentary dispersion glaucoma.
Clinical Relevance:
Because MYOC gene mutations may be responsible for a fraction (2 [8%] of 26) of families with POAG/JOAG, a molecular genetic diagnosis should be included in the management of patients with glaucoma.