Purpose: To investigate the prevalence of myocilin (MYOC) mutations in a population-based sample of open-angle glaucoma (OAG) cases and to describe a family with both juvenile and adult onset OAG caused by a mutation in MYOC.
Methods: MYOC was screened in cases derived from the Rotterdam Study in the Netherlands. Definite OAG was defined as a glaucomatous optic neuropathy together with a glaucomatous visual field defect. Upon the identification of the Asn480Lys mutation in one case, seven additional family members were studied. To test for a founder effect with earlier reported families with this mutation, the haplotypes of MYOC flanking markers D1S2851, D1S242, D1S218, and D1S1165 were compared.
Results: Seven sequence alterations in MYOC were found in 14 of 47 OAG cases; six of these were also found in controls. In one case, an Asn480Lys mutation was found. In relatives of the latter patient, the phenotype ranged from a glaucomatous optic neuropathy without visual field defect in a 70-year-old patient to severely affected optic discs and a remaining temporal remnant in a 34-year-old patient; those without the mutation had no signs of OAG. Haplotype analysis suggested a different origin of the mutation.
Conclusions: The prevalence of MYOC mutations (2.2%) was similar to that found in hospital-based studies. Although mutations in MYOC are rare, relatives carrying this mutation run a high risk of developing the disease. Instead of submitting all members of a family with the Asn480Lys mutation to frequent follow-up, medical care can be restricted to those carrying the mutation.