MYOC Mutation Research Articles

CYP1B1 and MYOC Gene Analysis of Patients with Primary Congenital Glaucoma in the Cukurova Region of Türkiye.

The aim of this study was to investigate the CYP1B1 and MYOC genes in patients with primary congenital glaucoma (PCG) from the Cukurova region (located in the south of Türkiye) and reveal the relationship between gene mutations and clinical severity of the disease. Molecular genetic and clinical study was conducted in 42 eyes of 26 patients who were followed for a diagnosis of PCG. The clinical diagnosis was concluded by ophthalmological examination under general anesthesia or slit-lamp biomicroscopy, gonioscopy, and measurement of the intraocular pressure. A CYP1B1 gene mutation was detected in 12 patients (46.2%). Two of these patients had a combination of CYP1B1 and MYOC mutations. The most common pathogenic variant, c.1405C > T (p.R469W) ( n = 5), was present in patients with mutations, and the prognosis was poor compared with other modifications ( p = 0.014). The second most common variant was c.3987G > A (p.G61E) ( n = 3), which was associated with a good prognosis. The incidence of buphthalmos and the mean horizontal corneal diameter were higher in patients with mutations in the CYP1B1 and MYOC genes. All parents were found to be carriers of the mutation gene. This is the report on molecular genetic analysis of PCG in the southern region of Türkiye. Some specific genetic variants may have an effect on the prognosis of the disease. However, patients without mutations in these case groups may have mutations in genes yet to be identified.

Synonymous Myocilin mutations break their silence in a Zambian population attending selected referral eye health facilities

Objective: Primary open-angle glaucoma in Zambia has an earlier age of onset and appears to be more clinically severe. Myocilin mutations are associated with primary open angle glaucoma in multiple populations. Therefore, we investigated the role of myocilin gene mutations in Primary Open Angle Glaucoma in a Zambian population. Methods: The unrelated primary open-angle glaucoma patients and unaffected controls recruited were from the University Teaching Hospitals Eye Hospital, Kitwe Teaching Eye Hospital and Lusaka Adventist Eye Hospital. A complete eye examination, including visual field assessment, was performed in all cases and controls.Genomic DNA was extracted from whole peripheral blood, then subjected to polymerase chain reaction to amplify exons, flanking introns and promoter regions of the myocilingene. The amplified products were screened for base mutations by auto sequence based on the Sanger method. The analyses of findings included odds ratios, chi-square, bivariate, multivariate and conditional logistic regression with 95% confidence interval and at a 5% level of significance.There was also a comparison between the identified mutations and the previously reported myocilinmutations. Results: Unrelated 165 Primary Open-Angle Glaucoma patients and unaffected 173 controls enrolled for the study. The analysis revealed 4 variants of MYOC mutations in 49 participants of the 338. The mutations included one synonymous (silent) mutation (Thr474Thr; 45/338) and three missense mutations (Ala446Thr; 16/338), (Leu158Arg; 4/338) and (Arg342Lys; 1/338). The study observed two previously reported mutations, Ala446Thr and Arg342Lys, as glaucoma causing mutations. The missense mutation, Ala446Thr, was found in 16 participants who also had silent mutations broken down as eight cases and eight controls. One control had two variants, Ala446Thr and Arg342Lys. Twenty (20) controls and 25 cases had the synonymous or silent (neutral) mutation, (Thr474Thr). The occurrence of Thr474Thr and Ala446Thr in the same cases and controls was compelling evidence to think that the synonymous mutations were not as silent as previously reported. The Thr474Thr and Ala446Thr mutations exhibited identical primary open-angle glaucomaphenotypic features in both cases and controls. In the remaining 17 cases and 12 controls the phenotype were still the same. The clinical profile in Thr474Thr mutation was statistically significant for female gender, younger age group (<40 years), older age group (≥ 65 years), positive family history, poor visual acuity, severe visual field changes, diffuse retinal nerve fibre layer defects, peripapillary atrophy surrounding the optic nerve head and high cup disc ratio between 0.8 and 1.0 Conclusions: The silent myocilin mutations, Thr474Thr, break their silence in a Zambian population. The silent mutation Thr474Thr found was associated with primary open-angle glaucoma phenotype and appeared to be a glaucoma-causing.

Glaucoma gene mutations and their association with angle dysgenesis

AbstractAngle dysgenesis is associated with developmental immaturity of the outflow pathways regulated by genes, which can only be ascertained with the help of histopathological studies. Mutations in some of the commonly associated genes with glaucoma, namely CYP1B1,FOXC1 PITX2, and TEK have been shown to be associated with developmental abnormalities in the outflow pathways in experimental studies. The severity of angle dysgenesis has been correlated on histopathology with certain CYP1B1 gene mutations in patients with Primary congenital glaucoma (PCG). Though MYOC mutations are known to be associated with Juvenile onset open angle glaucoma (JOAG) and even with PCG, no studies have shown the involvement of MYOC mutations in causing angle dysgenesis. There is only one histopathological report of a JOAG patient with MYOC Tyr453His mutation, where no apparent changes of the Trabecular meshwork(TM) or Sclemm's canal were noted though intense MYOC immune‐reactivity was observed at the TM. Histopathological studies for angle dysgenesis in human glaucomatous eyes are difficult to perform and are inherently associated with tissue handling artefacts. While grossly identifiable features of Ange dysgenesis on ASOCT (ADoA) have been described before, many subtle changes may also be present on ASOCT scans which are challenging to detect or precisely quantify by human observers.We studied the ASOCT scans of patients with open angle glaucoma diagnosed between 10 to 40 years of age, who had undergone Whole Exome Sequencing (WES) followed by a bioinformatics analysis and were found to harbour a mutation (that was pathogenic) in a known glaucoma gens. We used Deep learning (DL) models to detect ADoA.We detected MYOC mutations in 15 patients, 10 had CYP1B1, 2 had FOXC1 and 2 had LTBP2 mutation. Among these patients, angle dysgenesis on ASOCT was observed as predicted by the DL models, among all patients with known gene mutations. Overall, our DL Model was predictive of angle dysgenesis in 81% scans among MYOC positive patients, 89% CYP1B1 patients, 85% FOXC1 and 96% among those with LTBP2 mutation on an average.Our findings demonstrated that different gene mutations affect different parts of the proximal outflow pathways. While CYP1B1 and LTBP2 was found to affect primarily the SC morphology, the MYOC and FOXC1 were found to be associated with morphological variations in the TM, since the SC in the latter was normally developed.

Juvenile glaucomas and multi locus disease causing genomic variations

AbstractPurpose: Multilocus disease‐causing genomic variations (MGVs) and multiple genetic diagnoses (MGDs) are increasingly being recognized in individuals and families with Mendelian disorders. This can mainly be attributed to the widespread use of next generation sequencing (NGS) for the evaluation of these disorders. We conducted an NGS study of 40 juvenile onset open angle glaucoma (JOAG) families to evaluate the known and unknown gene mutations.Methods: Whole Exome sequencing was undertaken for 40 unrelated trios (proband and both parents) where the proband had JOAG. Out of these, eight were autosomal dominant, while rest were non familial.Results: Out of the 8 autosomal dominant JOAG families, MYOC mutations were detected in 3 (37.5%) and LTBP2 in 1 (12.5%). The family with LTBP2 mutation also had a MYOC mutation. One autosomal dominant family (12.5%) out of 8 had a rare EFEMP1 mutation in both affected father and daughter. The daughter also had Stickler syndrome (STL), that was later identified on observing a pathogenic COL11A1 mutation.Conclusions: These findings underline the importance of genetic evaluation in systematic phenotyping families with JOAG for MGVs and MGDs.

Structure‒function‒pathogenicity analysis of C-terminal myocilin missense variants based on experiments and 3D models.

MYOC is a common pathogenic gene for primary open-angle glaucoma and encodes the protein named myocilin. Multiple MYOC variations have been found, with different clinical significance. However, the pathogenesis of glaucoma induced by MYOC mutations has not been fully clarified. Here, we analyze the molecular and cellular biological differences caused by multiple variant myocilins, including protein secretion characteristics, structural changes, subcellular localization, cellular autophagic activity and oxidative stress. Denaturing and nondenaturing electrophoresis showed myocilin to be a secreted protein with the tendency to self-oligomerize. The full-length myocilin and its C-terminal cleavage fragment are secreted. Secretion analysis of 23 variant myocilins indicated that secretion defects are closely related to the pathogenicity of MYOC variants. Structural analysis showed that the alteration of steric clash is associated with the secretion characteristics and pathogenicity of myocilin variants. Immunocytochemistry results demonstrated that mutated myocilins are retained in the endoplasmic reticulum and disrupt autophagy. MTT assay, MitoTracker staining, and DCFH-DA staining showed increased oxidative injury in cells expressing MYOC mutants. Taken together, MYOC mutations are able to induce cell dysfunction via secretion defects and intracellular accumulation resulting from steric clash alterations.

Age at Glaucoma Diagnosis in Germline Myocilin Mutation Patients: Associations with Polymorphisms in Protein Stabilities.

Glaucoma is the leading cause of irreversible blindness worldwide, with elevated intraocular pressure (IOP) as the only known modifiable risk factor. Trabecular meshwork (TM)-inducible myocilin (the MYOC gene) was the first to be identified and linked to juvenile and primary open-angle glaucoma. It has been suggested that mutations in the MYOC gene and the aggregation of mutant myocilin in the endoplasmic reticulum (ER) of TM may cause ER stress, resulting in a reduced outflow of aqueous humor and an increase in IOP. We selected 20 MYOC mutations with experimentally determined melting temperatures of mutated myocilin proteins. We included 40 published studies with at least one glaucoma patient with one of these 20 MYOC mutations and information on age at glaucoma diagnosis. Based on data from 458 patients, we found that a statistically significant but weak correlation was present between age and melting temperature based on various assumptions for age. We therefore conclude that genetic analysis of MYOC mutations alone cannot be used to accurately predict age at glaucoma diagnosis. However, it might be an important prognostic factor combined with other clinical factors for critical and early detection of glaucoma.

Genetic Determinants of Intraocular Pressure.

Intraocular pressure (IOP) is the cardinal and only modifiable risk factor for glaucoma, the leading cause of irreparable blindness worldwide. Twin and family studies estimate the heritability of IOP to be 40-70%, and linkage studies for IOP have identified numerous loci. Mutations in MYOC can cause markedly elevated IOP and aggressive glaucoma often requiring surgical intervention. However, the majority of the genetic basis for raised IOP and glaucoma in populations is complex, and recent large genome-wide association studies (GWASs) have identified over 100 common variants that contribute to IOP variation. In combination, these loci are predictive for primary open-angle glaucoma in independent populations, achieving an area under the receiver operating characteristic curve of 76% for high-pressure primary open-angle glaucoma; this suggests the possibility of targeted screening in the future. Additionally, GWAS findings have identified important biological pathways underlying IOP regulation, including lymphangiogenesis and lipid metabolism, providing novel targets for new therapies.

Systemic Genotype-Phenotype Analysis of MYOC Variants Based on Exome Sequencing and Literature Review.

This study aims to characterize disease-causing variants in the myocilin gene (MYOC), which is associated with autosomal dominant primary open-angle glaucoma (adPOAG). Case-control study. MYOC variants were collected from in-house exome sequencing data of 7092 individuals. Genotype-phenotype analysis and bioinformatics evaluation were used to distinguish potential pathogenic variants for POAG from others. MYOC mutations in published works of literature were also systemically analyzed. In total, 53 variants in MYOC were detected in the 7092 subjects, including 45 rare variants (MAF < 0.01) and 8 polymorphisms (MAF ≥ 0.01), or 48 missense variants and 5 truncation variants. There was no difference in the frequency of the 8 polymorphisms between subjects with and without POAG (P > 0.05). The total number of rare MYOC variants was significantly higher in POAG than that in in-house controls (P = 3.31E-14). The pathogenic/likely pathogenic variants (p.P254T, p.S341P, p.G367R, p.P370L, p.D378G, p.C433Y, and p.L486F) were exclusively present in 8 POAG but absent in in-house controls (P = 2.79E-10). Rare truncation MYOC variants were not enriched in POAG as compared with those in in-house controls (P = 0.28). Further analysis of previously reported MYOC variants suggested that pathogenic/likely pathogenic variants were enriched in the conserved olfactomedin domain. Truncation MYOC variants were scattered in the coding region, where only p.Q368∗ had relatively strong evidence to be causative for adPOAG, whereas most others are questionable. Most MYOC variants contributing to adPOAG could be characterized as rare missense variants located in OLF-domain and predicted to be damaging through multiple tools. The effect of other variants, especially for truncation variants (except for p.Q368∗) need further clarification.

Is there a place for polygenic risk scores and gwas in modern genetic testing?

Traditionally genetic testing has focused on rare high penetrance mutations such as BRCA1 mutations conferring risk of breast/ovarian cancer or MYOC mutations conferring risk of glaucoma. However, most Australians affected by common diseases such as these do not carry these mutations. Instead, most people are at high genetic risk due to the cumulative effect of many polygenes (that is, variants of individually small effect on risk). Recent genome-wide association studies have identified polygenes for virtually every complex human trait. There has been considerable recent excitement about polygenic risk scores (PRS) – these provide an index of genetic risk based on the cumulative effect of many polygenes. While there are now PRS for many diseases, their translational utility can be limited due to poor predictive performance or because of a lack of real world consequences. In my talk I will discuss applications of PRS across a range of traits including eye disease and cancer. In a general population setting I will show there are exciting opportunities for PRS to be used in improving risk stratification and screening. In the ‘high penetrance mutation’ setting, I will show that mutation penetrance can vary dramatically with PRS values, with important consequences for genetic testing.

Cross-talk between MYOC p. Y437H mutation and TGF-β2 in the pathology of glaucoma.

Objective: To identify the interaction between the MYOC Y437H mutation and TGF-β2 in a family with primary open-angle glaucoma (POAG).Methods: The MYOC Y437H mutation was identified in a family with POAG; the family was a fourth-generation family with 27 members, of which 6 members were affected. Analysis focused on the secreted myocilin protein and TGF-β2 found in the aqueous humor. Samples were taken both from normal controls and MYOC mutant carriers and cross-talk between MYOC Y437H and TGF-β2 were evaluated in the trabecular meshwork (TM) cells.Results: Aqueous humor secreted myocilin protein levels were reduced while TGF-β2 levels were increased in patients with the MYOC (c.1309T>C) mutation. This inverse relationship indicated that elevated TGF-β2 may be an important pathogenic mechanism in the progression of myocilin-related POAG. In TM cells expressing the MYOC Y437H mutant, exogenous TGF-β2 also significantly increased myocilin expression as well as the endoplasmic reticulum (ER) stress markers GRP94 and CHOP. This increase in TGF-β2 was also associated with increased cell death in cells carrying the MYOC Y437H mutation.Conclusion: These data collectively suggest that the mutual interaction between glaucomatous MYOC mutation and TGF-β2 contributed to the cell death of TM cells. This relationship also provides a new, therapeutic targets for the treatment of glaucoma.

Clinical application of NGS-based SNP haplotyping for the preimplantation genetic diagnosis of primary open angle glaucoma

ABSTRACTThe current study describes a successful case of preimplantation genetic diagnosis (PGD) of primary open angle glaucoma (POAG) and verifies the efficiency of next-generation sequencing (NGS)-based haplotyping for PGD of POAG. In this study, we applied NGS as part of PGD to effectively detect POAG prior to embryo implantation and avoid the prospect of pregnancy termination in event of vertical inheritance of POAG. We used the technique of multiple annealing and looping based amplification cycles (MALBAC) to conduct whole genome amplification (WGA) and to reduce the allele dropout (ADO). We also employed Sanger sequencing to directly detect the mutation c.1109 C > T in MYOC and NGS-based single nucleotide polymorphism (SNP) haplotyping to distinguish the chromosomes that carried the mutation. Copy number variation (CNV) analysis was carried out to determine the copy number of embryos’ chromosomes. Of the 4 blastocysts obtained in this study, only 2 (sample 5 and 7) could be successfully amplified by WGA. CNV results indicated that chromosomes of both these samples were balanced (46, XN). Sanger sequencing and NGS-based SNP haplotyping confirmed that sample 7 carried the mutation c.1109 C > T in MYOC, while sample 5 did not. Moreover, no ADO was observed. Thus, blastocyst 5 was transferred into the uterus of the patient, and a healthy baby without the MYOC mutation c. 1109C>T was born 39 weeks after transplantation. Our study suggests that NGS-based SNP haplotyping is an effective technique for the PGD of POAG.Abbreviations: PGD: preimplantation genetic diagnosis; POAG: primary open angle glaucoma; NGS: next-generation sequencing; MALBAC: multiple annealing and looping based amplification cycles chemistry; WGA: whole genome amplification; ADO: allele dropout; SNP: single nucleotide polymorphism; CNV: copy number variation; MYOC: Myocilin; OPTN: Optineurin; WDR36: WD repeat domain 36; CYP1B1: Cytochrome P450 1 B Chain; ICSI: intracytoplasmic sperm injection; TFNA: testicular fine-needle aspiration; TE: trophectoderm; PCR: polymerase chain reaction

The clinical feature of myocilin Y437H mutation in a Chinese family with primary open-angle glaucoma

PurposeTo characterise the genotype(s), phenotype(s) and age-related penetrance of glaucoma in a Chinese family with primary open-angle glaucoma (POAG).MethodsRecruited from a Chinese family spanning four generations, 7 individuals with POAG,...

Congenital glaucoma and CYP1B1: an old story revisited.

Primary congenital glaucoma is a trabecular meshwork dysgenesis with resultant increased intraocular pressure and ocular damage. CYP1B1 mutations remain the most common identifiable genetic cause. However, important questions about the penetrance of CYP1B1-related congenital glaucoma remain unanswered. Furthermore, mutations in other genes have been described although their exact contribution and potential genetic interaction, if any, with CYP1B1 mutations are not fully explored. In this study, we employed modern genomic approaches to re-examine CYP1B1-related congenital glaucoma. A cohort of 193 patients (136 families) diagnosed with congenital glaucoma. We identified biallelic CYP1B1 mutations in 80.8% (87.5 and 66.1% in familial and sporadic cases, respectively, p < 0.0086). The large family size of the study population allowed us to systematically examine penetrance of all identified alleles. With the exception of c.1103G>A (p.R368H), previously reported pathogenic mutations were highly penetrant (91.2%). We conclude from the very low penetrance and genetic epidemiological analyses that c.1103G>A (p.R368H) is unlikely to be a disease-causing recessive mutation in congenital glaucoma as previously reported. All cases that lacked biallelic CYP1B1 mutations underwent whole exome sequencing. No mutations in LTBP2, MYOC or TEK were encountered. On the other hand, mutations were identified in genes linked to other ophthalmic phenotypes, some inclusive of glaucoma, highlighting conditions that might phenotypically overlap with primary congenital glaucoma (SLC4A4, SLC4A11, CPAMD8, and KERA). We also encountered candidate causal variants in genes not previously linked to human diseases: BCO2, TULP2, and DGKQ. Our results both expand and refine the genetic spectrum of congenital glaucoma with important clinical implications.

A recurrent G367R mutation in MYOC associated with juvenile open angle glaucoma in a large Chinese family.

To identify the mutations of MYOC, OPTN, CYP1B1 and WDR36 in a large Chinese family affected by juvenile open angle glaucoma (JOAG). Of 114 members of one family were recruited in this study. Blood samples from twelve members of this pedigree were collected for further research. As a control, 100 unrelated subjects were recruited from the same hospital. The exon and flanking intron sequences of candidate genes were amplified using the polymerase chain reaction and direct DNA sequencing. The proband (III:10) was a seventy-three years old woman with binocular JOAG at the age of 31. A recurrent heterozygous mutation (c.1099G>A) of MYOC was identified in the three JOAG patients and another suspect. This transition was located in the first base pair of codon 367 (GGA>AGA) in exon 3 of MYOC and was predicted to be a missense substitution of glycine to arginine (p.G367R) in myocilin. Mutations in OPTN, CYP1B1 or WDR36 were not detected in this study. The G367R mutation was not present in unaffected family members or in 100 ethnically matched controls. Other variants of the coding regions of candidate genes were not detected in all participants. To date, this family was the largest to have been identified as carrying a certain MYOC mutation in China, further evidence of a founder effect for the G367R MYOC mutant was provided by our data. A MYOC c.1099G>A mutation in an autosomal dominant JOAG family is identified and the characteristic phenotypes among the patients are summarized. Genetic testing could be utilized in high-risk populations and be helpful not only for genetic counseling, but also for early diagnosis and treatment of affected patients or carriers of inherited JOAG.

Detection of mutations in MYOC, OPTN, NTF4, WDR36 and CYP1B1 in Chinese juvenile onset open-angle glaucoma using exome sequencing

Juvenile onset open-angle glaucoma (JOAG) affects patients before 40 years of age, causing high intraocular pressure and severe optic nerve damage. To expand the mutation spectrum of the causative genes in JOAG, with a view to identify novel disease-causing mutations, we investigated MYOC, OPTN, NTF4, WDR36 and CYP1B1 in a cohort of 67 unrelated Chinese JOAG patients. Whole exome sequencing was used to identify possible pathogenic mutations, which were further excluded in normal controls. After sequencing and the use of a database pipeline, as well as predictive assessment filtering, we identified a total of six mutations in three genes, MYOC, OPTN and CYP1B1. Among them, 2 heterozygous mutations in MYOC (c. 1109C > T, p. (P370L); c. 1150G > C, p. (D384H)), 2 heterozygous mutations in OPTN (c. 985A > G, p.(R329G); c. 1481T > G, p. (L494W)) and 2 homozygous mutations in CYP1B1 (c. 1412T > G, p.(I471S); c. 1169G > A, p.(R390H)) were identified as potentially causative mutations. No mutation was detected in NTF4 or WDR36. Our results enrich the mutation spectra and frequencies of MYOC, OPTN and CYP1B1 in JOAG among the Chinese population. Further studies are needed to address the pathogenicity of each of the mutations detected in this study.

Genetics of glaucoma.

Genetic and genomic studies, including genome-wide association studies (GWAS) have accelerated the discovery of genes contributing to glaucoma, the leading cause of irreversible blindness world-wide. Glaucoma can occur at all ages, with Mendelian inheritance typical for the rare early onset disease (before age 40) and complex inheritance evident in common adult-onset forms of disease. Recent studies have suggested possible therapeutic targets for some patients with early-onset glaucoma based on the molecular and cellular events caused by MYOC, OPTN and TBK1 mutations. Diagnostic genetic tests using early-onset glaucoma genes are also proving useful for pre-symptomatic disease detection and genetic counseling. Recent GWAS completed for three types of common adult-onset glaucoma have identified novel loci for POAG (primary-open-angle glaucoma) (ABCA1, AFAP1, GMDS, PMM2, TGFBR3, FNDC3B, ARHGEF12, GAS7, FOXC1, ATXN2, TXNRD2); PACG (primary angle-closure glaucoma (EPDR1, CHAT, GLIS3, FERMT2, DPM2-FAM102); and exfoliation syndrome (XFS) glaucoma (CACNA1A). In total sixteen genomic regions have been associated with POAG (including the normal tension glaucoma (NTG) subgroup), 8 with PACG and 2 with XFS. These studies are defining important biological pathways and processes that contribute to disease pathogenesis.

CYP1B1 and myocilin gene mutations in Egyptian patients with primary congenital glaucoma

PurposePrimary congenital glaucoma (PCG) accounts for 26–29% of childhood blindness in Egypt. The identification of disease causing mutations has not been extensively investigated. We aimed to examine the frequency of CYP1B1 and MYOC mutations in PCG Egyptian patients, and study a possible genotype/phenotype correlation. MethodsNinety-eight patients with PCG diagnosed at the Ophthalmology department of Alexandria Main University Hospital were enrolled. Demographic and phenotypic characteristics were recorded. Patients and 100 healthy subjects (control group) were screened for two mutations in CYP1B1 gene (G61E, R368H) and one mutation in MYOC gene (Gln48His) using polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP). Phenotypic characteristics pertaining to disease severity were compared. ResultsNineteen patients (19%) with PCG were found positive for one or more of the mutations screened for. Seven patients (7%) were homozygous for the G61E mutation. Ten patients (10%) were heterozygous; 6 for the G61E mutation, 2 for the R368H mutation and 2 for the Gln48His mutation. Two patients (2%) were double heterozygotes harboring a R368H as well as a Gln48His mutation. The most common mutation observed was the G61E in 13 patients; 7 homozygotes and 6 heterozygotes for the mutation. The control group were negative for all mutations screened for.No significant correlations between the mutations and phenotype severity were detected. A statistically significant positive correlation however was found between the different mutations and each of the IOP and the cup/disk ratio. ConclusionThe current study further endorses the role of CYP1B1 mutations in the etiology of PCG among Egyptian patients and is the first study to report MYOC gene mutation in Egyptian patients with PCG.

Rare FOXC1 variants in congenital glaucoma: identification of translation regulatory sequences.

Primary congenital glaucoma (PCG) is the cause of a significant proportion of inherited visual loss in children, but the underlying mechanism is poorly understood. In this study, we assessed the relationship between PCG and FOXC1 variants by Sanger sequencing the proximal promoter and transcribed sequence of FOXC1 from a cohort of 133 PCG families with no known CYP1B1 or MYOC mutations. The pathogenicity of the identified variants was evaluated by functional analyses. Ten patients (7.5%) with no family history of glaucoma carried five different rare heterozygous FOXC1 variants with both increased (rs77888940:C>G, c.-429C>G, rs730882054:c.1134_144del(CGGCGGCGCGG), p.(G380Rfs*144) and rs35717904:A>T, c.*734A>T) and decreased (rs185790394: C>T, c.-244C>T and rs79691946:C>T, p.(P297S)) transactivation, ranging from 50 to 180% of the wild-type activity. The five variants did not show monogenic segregation, and four of them were absent in a control group (n=233). To the best of our knowledge, one of these variants (p.(G380Rfs*144)) has not previously been described. One of the FOXC1 variant carriers (p.(P297S)) also coinherited a functionally altered rare PITX2 heterozygous variant (rs6533526:C>T, c.*454C>T). Bioinformatics and functional analyses provided novel information on three of these variants. c.-429C>G potentially disrupts a consensus sequence for a terminal oligopyrimidine tract, whereas c.-244C>T may alter the RNA secondary structure in the 5'-untranslated region (UTR) that affects mRNA translation. In addition, p.(G380Rfs*144) led to increased protein stability. In summary, these data reveal the presence of translation regulatory sequences in the UTRs of FOXC1 and provide evidence for a possible role of rare FOXC1 variants as modifying factors of goniodysgenesis in PCG.

Whole exome sequencing reveals a novel de novo FOXC1 mutation in a patient with unrecognized Axenfeld–Rieger syndrome and glaucoma

We report the identification of a novel mutation in the fork-head box C1 (FOXC1) gene which occurred de novo in an Italian patient with unrecognized Axenfeld–Rieger syndrome. He was previously diagnosed as having late recognized primary congenital glaucoma at the age of 14years and was subsequently subjected to multiple surgical interventions due to uncontrolled intraocular pressure and progressive visual field loss.After exclusion of mutations in CYP1B1 and MYOC, trio-whole-exome sequencing revealed de novo in frame deletion in the coding region of the FOXC1 gene (c.407_409delGTC, p.V137del) leading to a deletion of the evolutionary conserved amino acid Valine at position 137 of the protein. Molecular modeling predicted that Val137 deletion impairs FOXC1 DNA-binding capacity and transcriptional activation.Since loss-of-function mutations in FOXC1 are associated with Axenfeld–Rieger syndrome, the genetic findings in combination with re-evaluation of the patient's clinical data resulted in a corrected diagnosis of Axenfeld–Rieger syndrome with developmental glaucoma. We therefore suggest that in addition to CYP1B1 and MYOC, FOXC1 should be included in the genetic analysis of cases with unclear glaucomatous phenotypes to ensure proper diagnosis, adequate treatment and appropriate genetic counseling.

Glaucoma in iran and contributions of studies in iran to the understanding of the etiology of glaucoma.

Epidemiologic and genetic/molecular research on glaucoma in Iran started within the past decade. A population-based study on the epidemiology of glaucoma in Yazd, a city in central Iran, revealed that 4.4% of studied individuals were affected with glaucoma: 1.6% with high tension primary open angle glaucoma (POAG), 1.6% with normal tension POAG, and 0.4% each with primary angle closure glaucoma (PACG) and pseudoexfoliation glaucoma (PEXG), and other types of secondary glaucoma. Two notable observations were the relatively high frequency of normal tension glaucoma cases (1.6%) and the large fraction of glaucoma affected individuals (nearly 90%) who were unaware of their condition. The first and most subsequent genetic studies on glaucoma in Iran were focused on primary congenital glaucoma (PCG) showing that cytochrome P450 1B1 (CYP1B1) is the cause of PCG in the majority of Iranian patients, many different CYP1B1 mutations are present among Iranian patients but only four mutations constitute the vast majority, and the origins of most mutations in the Iranians are identical by descent (IBD) with the same mutations in other populations. Furthermore, most of the PCG patients are from the northern and northwestern provinces of Iran. A statistically significant male predominance of PCG was observed only among patients without CYP1B1 mutations. Clinical investigations on family members of PCG patients revealed that CYP1B1 mutations exhibit variable expressivity, but almost complete penetrance. A great number of individuals harboring CYP1B1 mutations become affected with juvenile onset POAG. Screening of JOAG patients showed that an approximately equal fraction of the patients harbor CYP1B1 and (myocilin) MYOC mutations; MYOC is a well-known adult onset glaucoma causing gene. Presence of CYP1B1 mutations in JOAG patients suggests that in some cases, the two conditions may share a common etiology. Further genetic analysis of Iranian PCG patients led to identification of Latent-transforming growth factor beta-binding protein 2 (LTBP2) as a causative gene for both PCG and several diseases which are often accompanied by glaucomatous presentations, such as Weill-Marchesani syndrome 3 (WMS3). The findings on LTBP2 have contributed to recognize the importance of the extracellular matrix in pathways leading to glaucoma.