Prevalence of Myocilin Gene Mutation in Adult-Onset Primary Open Angle Glaucoma and Non-glaucoma Subjects Who are Indigenes of Rivers State, Nigeria

A. A. Onua

School of Public Health, University of Port Harcourt, Nigeria.

C. N. Pedro-Egbe *

Department of Ophthalmology, University of Port Harcourt, Nigeria.

*Author to whom correspondence should be addressed.


Background: Glaucoma is the leading cause of irreversible blindness incapacitating over 80 million people worldwide. Several pathogenetic mechanisms have been postulated to explain the optic nerve damage that occur in POAG among which genetic predisposition is prominent. Gene-Linkage-based studies have identified genes associated with POAG: Myocilin, Optineurin, WDR36, Tank-Binding Kinase (TBK1) and APbb-2.

Objective: To investigate the prevalence of myocilin gene mutation in adult-onset POAG patients and non-glaucoma subjects who are indigenes of Rivers State.

Methodology: In this comparative cross-sectional study, 393 POAG patients attending the Glaucoma Clinic of UPTH, were compared with 393 age and sex- matched phenotypically normal participants. Clinical assessment combined with findings from clinical records were used. Venous blood was obtained for genomic analyses. Extracted DNA were sequenced with specific primers for myocilin and polymerase chain reaction. Zymo-Bead Genomic DNA kit protocol was used to detect allelic differences.

Results: Total of 786 participants participated in the study. The mean age was 59.8 ± 11.8 years. The prevalence of myocilin gene mutation (MYOC) in the study population was 5.3%, in the POAG group was 8.4%, and 2.3% in the non-glaucoma group. This observed difference was statistically significant (p=0.001). Location of the mutant myocilin gene was in GLC1A 171638779, 171638703, 171638610 and 171638608.

Conclusion: Mutations in myocilin gene are associated with adult-onset POAG in Rivers State. It’s relevance as a biomarker for diagnosis of adult-onset POAG needs further investigations.  

Keywords: Prevalence, myocilin gene mutation, adult-onset primary open angle glaucoma, Rivers State indigenes

How to Cite

Onua, A. A., & Pedro-Egbe, C. N. (2023). Prevalence of Myocilin Gene Mutation in Adult-Onset Primary Open Angle Glaucoma and Non-glaucoma Subjects Who are Indigenes of Rivers State, Nigeria. Asian Journal of Research and Reports in Ophthalmology, 6(1), 12–23. Retrieved from


Download data is not yet available.


World Health Organization. Magnitude and cause of visual impairment. WHO fact Sheet No. 282. Geneva: WHO; 2020.

Available from: [accessed 2/3/ 2021]

Kyari F, Gudlavalleti MV, Sivsubramaniam S, Gilbert CE, Abdull MM, Entekume G et al. Prevalence of blindness and visual impairment in Nigeria: the National Blindness and Visual Impairment Study. Invest Ophthalmol Vis Sci. 2009;50(5): 2033-9.

DOI: 10.1167/iovs.08-3133, PMID 19117917

Ashaye A. Glaucoma blindness: facts, fancies and fables. 12th Faculty Lecture. Ibadan: Faculty of Ophthalmology, National Postgraduate Medical College of Nigeria.BookBuilders:1-48;2010.

Allingham RR, Liu Y, Rhee DJ. The genetics of primary open angle glaucoma: a review. Exp Eye Res. 2009;88(4):837-44.

DOI: 10.1016/j.exer.2008.11.003, PMID 19061886.

Bowling B. Kanski’s clinical ophthalmology. A systemic approach. 8th ed, Edinburgh. Elsevier Butterworth-Heinemann; 2016; 306-66.

Fan BJ, Wiggs JL. Glaucoma: genes, phenotypes, and new directions for therapy. J Clin Invest. 2010;120(9):3064-72.

DOI: 10.1172/JCI43085, PMID 20811162

Fingert JH. Primary open-angle glaucoma genes. Eye (Lond). 2011;25(5):587-95.

DOI: 10.1038/eye.2011.97, PMID 21562585

Monemi S, Spaeth G, DaSilva A, Popinchalk S, Ilitchev E, Liebmann J et al. Identification of a novel adult-onset primary open-angle glaucoma (POAG) gene on 5q22.1. Hum Mol Genet. 2005;14(6):725-33.

DOI:10.1093/hmg/ddi068, PMID 15677485

Liu Y, Hauser MA, Akafo SK, Qin X, Miura S, Gibson JR et al. Investigation of known genetic risk factors for primary open angle glaucoma in two populations of African ancestry. Invest Ophthalmol Vis Sci. 2013;54(9):6248-54.

DOI:10.1167/iovs.13-12779,PMID:23963 167

Stone EM, Aldave AJ, Drack AV, Maccumber MW, Sheffield VC, Traboulsi E et al. Recommendations for genetic testing of inherited eye diseases: report of the American Academy of Ophthalmology task force on genetic testing. Ophthalmology. 2012;119(11):2408-10.

DOI: 10.1016/j.ophtha.2012.05.047, PMID 22944025

Fingert JH, Robin AL, Stone JL, Roos B, Davis LK, Scheetz TA. Copy number variations on Chromosom 12q14 patients with normal tension glaucoma. Hum Mol Genet. 2011.

DOI: 10.1093.

Kwon YH, Fingert JH, Kuehn MH, Alward WL. Primary open-angle glaucoma. N Engl J Med. 2009;360(11):1113-24.

DOI: 10.1056/NEJMra0804630, PMID 19279343.

Available: (Assessed 15/10/2022)

Allen KF, Gaier ED, Wiggs JL. Genetics of primary inherited disorders of the optic nerve: clinical applications. Cold Spring Harb Perspect Med. 2015;5(7):a017277.

DOI: 10.1101/cshperspect.a017277, PMID 26134840.

Kyari F, Entekume G, Rabiu M, Spry P, Wormald R, Nolan W et al. A Population-based survey of the prevalence and types of glaucoma in Nigeria: results from the Nigeria National Blindness and Visual Impairment Survey. BMC Ophthalmol. 2015;12(15):176.

DOI: 10.1186/s12886-015-0160-6.

Awoyesuku EA, Ejimadu CS. Visual disability in newly diagnosed primary open angle glaucoma (POAG) patients in a tertiary hospital in Nigeria. Niger J Med. 2012;21(1):78-80.

PMID 23301454.

Adekoya BJ, Shah SP, Onakoya AO, Ayanniyi AA. Glaucoma in Southwest Nigeria: clinical presentation, family history and perceptions. Int Ophthalmol. 2014; 34(5):1027-36.

DOI: 10.1007/s10792-014-9903-2, PMID 24442760.

Leske MC, Connell AM, Wu SY, Hyman LG, Schachat AP. Risk factors for open-angle glaucoma. The Barbados eye Study. Arch Ophthalmol. 1995;113(7):918-24.

DOI:10.1001/archopht.1995.01100070092031, PMID 7605285

Leske MC, Wu SY, Hennis A, Honkanen R, Nemesure B, BESs Study Group. Risk factors for incident open-angle glaucoma: the Barbados Eye Studies. Ophthalmology. 2008;115(1):85-93.

DOI: 10.1016/j.ophtha.2007.03.017, PMID 17629563

Challa P, Herndon LW, Hauser MA, Broomer BW, Pericak-Vance MA, Ababio-Danso B et al. Prevalence of myocilin mutations in adults with primary open-angle glaucoma in Ghana, West Africa. J Glaucoma. 2002;11(5):4: 6-20.

DOI: 10.1097/00061198-200210000-00008, PMID 12362081

Fingert JH, Héon E, Liebmann JM, Yamamoto T, Craig JE, Rait J et al. Analysis of myocilin mutations in 1703 glaucoma patients from five different populations. Hum Mol Genet. 1999;8(5):899-905.

Ennis S, Gibson J, Griffiths H, Bunyan D, Cree AJ, Robinson D et al. Prevalence of myocilin gene mutations in a novel UK cohort of POAG patients Eye Lond). 2010;24(2): 328-33.

DOI:10.1038/eye.2009.73, PMID:194078- 46