Myocilin analysis by DHPLC in French POAG patients: Increased prevalence of Q368X mutation

Abstract

Primary open-angle glaucoma (POAG) is a prevalent optic neuropathy with complex genetics. A small number of patients carry a mutation in the coding region of the myocilin (MYOC) gene. The nature and the frequency of these mutations, however, vary substantially, notably with the age at onset and the ethnic origin of the patients. Here, we showed that denaturing high performance liquid chromatography (DHPLC) is an appropriate method for screening carriers of MYOC mutations. We have applied the method to a group of 237 POAG patients and 108 control subjects from France. Mutations were found in 17 (7.5%) patients and in none of the controls. A single mutation, Q368X (c.1102C>T), accounted for the majority (12/17) of these mutations, corresponding to a frequency of 5% among POAG patients, the highest ever reported for this mutation. Furthermore, analysis of allelic associations at closely linked microsatellite markers indicated that most, if not all, patients inherited Q368X from a same ancestor. Five other patients carried four distinct mutations, including N480K (c.1440C>A) (2 cases), I499F (c.1495A>T), G367R (c.1099G>A) and T438I (c.1313C>T), which is reported here for the first time. Altogether, MYOC mutations in French patients were associated with a significantly increased intraocular pressure at diagnosis. In addition, the age at diagnosis of patients with a mutation other than Q368X was significantly younger than that of Q368X carriers or of patients with a normal MYOC. Based on these observations, a screening strategy of MYOC mutations in French POAG patients is briefly outlined.

Inhibition of Metabotropic Glutamate Receptor Signaling by the Huntingtin-binding Protein Optineurin

“…Single Nucleotide Polymorphism OPTN Variant Defective in Htt Binding-The OPTN gene was recently reported to possess both causal and risk-associated alleles for open angled glaucoma (20,30,31). We found that one missense single nucleotide polymorphism OPTN mutant, OPTN-H486R, demonstrated reduced association with N-Htt Q138 (52 Ϯ 20% of wild-type OPTN binding) but was unimpaired in either FLAG-mGluR1a or N-Htt Q15 binding (Fig.…”

“…Recent studies have demonstrated that single nucleotide polymorphism OPTN variants are associated with hereditary forms of normal tension glaucoma (20,30,31). Alterations in mGluR signaling are also implicated in contributing to the etiology of glaucoma (37).…”

CYP1B1 mutations in French patients with early-onset primary open-angle glaucoma

“…22 Probands of PCG families were reported previously. 18 A protocol approved by the Ethics Committee of Necker Medical School and in keeping with European legislation was followed.…”

“…The oven temperature and gradient conditions for heteroduplex detection were predicted with WaveMaker software (version 4.1.40) and specified experimentally as described previously. 22 Actual parameters for DHPLC analysis of CYP1B1 amplicons were established in this work and are listed in table 1. PCR products from DNA to be tested were mixed with an equimolar amount of PCR product from a DNA sample known to be unmutated.…”

Recurrent Myocilin Asn480Lys Glaucoma Causative Mutation Arises De Novo in a Family of Andean Descent

“…5,8 Early genetic diagnosis in glaucoma can help prevent irreparable ocular damage if caused by MYOC mutations, where elevation of intraocular pressure (IOP) can be quite pronounced and outcomes can be severe. 9 Prevalence of glaucoma varies among populations, showing values ranging from 1.7% to 2.1% for whites over the age of 40, to 4 times this percentage for populations of African descent. 10 There are ethnogeographic differences in distribution of MYOC mutations.…”