Identification of mutation of MYOC (c.1099G>A), a pedigree pathogenic gene of juvenile open angle glaucoma (JOAG): A case report

Abstract

Rationale: The MYOC gene is associated with juvenile open-angle glaucoma (JOAG). This study aims to provide genetic counseling for a Chinese JOAG family by detecting MYOC mutations to identify high-risk individuals for early JOAG intervention. It also supplements the clinical characteristics of glaucoma patients with MYOC gene mutations.

Patient concerns: A 43-year-old presented sought medical attention in a local hospital due to a 6-month decline in binocular vision. He was diagnosed as JOAG and underwent glaucoma surgery. The patient also had 11 family members with a history of JOAG.

Diagnoses: After sequencing the polymerase chain reaction products of the patient, MYOC c.1099 G > A (p.G367R) mutation was observed. That is consistent with a diagnosis of JOAG.

Intervention: Polymerase chain reaction analyses of 9 patients and 42 healthy family members were performed to explore potential mutations associated with familial JOAG.

Outcomes: JOAG assisted in diagnosing the III-5 proband. Genetic detection indicated that III-5 was exposed to a novel heterozygous missense mutation of MYOC (c.1099 G > A [p.G367R]). The co-segregation of this gene with the trait observed in the pedigree was verified. All 10 participants exhibiting this mutation had JOAG phenotypes, whereas other participants did not show this mutation. In terms of MYOC mutation c.1099 G > A (p.G367R), this mutation occurred when the 1099th nucleotide in the encoding zone of MYOC changed from G to A. Moreover, the 367th amino acid coded by this base got mutated from glycine to arginine. DNAMAN sequence homology results showed that the G residues of MYOC: 367 were significantly conserved among different species. In addition, 3D protein conformation predicted that these mutations could decrease protein stability.

Lessons: MYOC c.1099 G > A was identified as a pathogenic gene of JOAG in this pedigree. The addition of the MYOC mutant spectrum to JOAG in the Chinese population facilitates a complete understanding of the molecular pathogenesis and clinical diagnosis of MYOC.