Introduction: Primary open-angle glaucoma is the most frequent subtype of glaucoma. Relatives of primary open-angle glaucoma patients have an increased risk of developing the disease, suggesting a genetic predisposition to the disease. MYOC was the first primary open-angle glaucoma-causing gene identified. This study aimed to identify sequence variations in the MYOC gene that may be responsible for the phenotype in a group of primary open-angle glaucoma patients from the Centre Region of Portugal.Material and Methods: The three coding exons and the proximal splicing junctions of the MYOC gene were studied using a PCR sequencing approach in a group of 99 primary open-angle glaucoma patients.Results: The sequencing analysis enabled the identification of 20 variants, including four in the promoter region, seven in the introns and nine in exons one and three, of which four were missense variants.Discussion: Initially, all four missense sequence variations identified were considered candidates to glaucoma causing disease mutations. However, after literature review, only variant c.1334C>T (Ala445Val) remained as likely responsible for mild late-onset normal tension glaucoma.Conclusion: This is the first study performed in a group of primary open-angle glaucoma patients from the Centre Region of Portugal, contributing to the identification of one genetic variant in the MYOC gene and reinforcing the hypothesis that normal tension glaucoma could be also due to MYOC gene mutations.