Objective: To present the phenotype of two patients with primary open angle glaucoma (POAG) caused by a mutation of the myocilin/trabecular meshwork-inducible glucocorticoid response (MYOC/TIGR) gene.

Methods: Complete ocular examinations were performed on the 13-year-old proband, her father, mother, and sister. DNA analysis was performed to detect the mutant gene.

Results: The proband and her father were found to have a mutation of the MYOC/TIGR gene. Both patients carried a heterozygous mutation in the 1,109th nucleotide, which corresponds to the 370th amino acid residue of the MYOC/TIGR gene. The clinical characteristics of both patients were: (1) development of POAG at an early age, (2) high peaks of intraocular pressure. and (3) poor response to medical treatment.

Conclusions: The phenotype of these patients with a mutation of the MYOC/TIGR gene agreed with reports of other patients with mutations at other loci in this gene. The discovery of the MYOC/TIGR gene not only makes early detection of glaucoma possible, but also presents a new direction for investigating the pathogenesis of glaucoma.