Bilateral helicoid peri-papillary sub-retinal fibrosis due to a biallelic NR2E3 mutation: Describing variable expressivity of a mutation

BACKGROUND

To describe different clinical presentations of a same NR2E3 recessive mutation in two families and within one family.

DESIGN

Interventional family study.

RESULTS

Our first case was a one-year-old male child with high hyperopia and refractive accommodative esotropia. In retinal examination, peri-papillary sub-retinal fibrosis with a helicoid configuration was observed in both eyes. The parents and the only sibling had no pathologic findings in the eyes. The child showed to have severely reduced responses in both photopic and scotopic electroretinogram components. In the genetic investigation, a homozygous autosomal recessive mutation in the NR2E3 gene (IVS1-2A > C) was discovered in the affected child, while the other family members were heterozygous for this mutation. We followed up with the patient for 3 years and no new lesion developed during this period. The second case was a 13-year-old male child referred to the retina clinic for decreased vision in the right eye. In retina examination, there were nummular pigmentary changes at the level of retinal pigment epithelium and along the vascular arcades with foveo-schitic changes in both eyes. A choroidal neovascularization (CNV) was noticed in the macula of his right eye. The genetic evaluation proved the same mutation in the NR2E3 gene as in the first case. Family history was remarkable for an uncle, an aunt, and two cousins with night blindness.

CONCLUSION

Same NR2E3 gene mutation can cause heterogeneous clinical manifestations such as slight retinal changes in the absence of any visual symptoms to high hyperopia associated with helicoid peri-papillary sub-retinal fibrosis.

Expression Profiling of ADAMTS (L) Superfamily of Genes in Various Human Eye Tissues

Background

A disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) is a superfamily of extracellular proteinases found in both mammals and invertebrates. Although there is some evidence about the role of ADAMTSs in ocular diseases such as glaucoma and ectopia lentis, but there is little information about the expression patterns of ADAMTS-1-20 and ADAMTS-like (ADAMTSL-1-6 and PAPLN) genes in human ocular tissues. This study aimed to evaluate the expression profiling of ADAMTS(L) superfamily of genes in different ocular tissues based on age.

Methods

In 2019, nine human donated eye globes were provided from the Central Eye Bank of Iran, and were divided into three different groups based on age (under 3 yr old, between 20 to 50 and upper 50 yr old). To assess expression patterns of ADAMTS(L) genes in different ocular tissues including trabecular meshwork, lens, retinal pigment epithelium, macula, and optic nerve in the three age groups, total RNA was extracted from the tissues and reverse transcription polymerase chain reaction followed by Real-time PCR was performed.

Results

We demonstrated not only each member of ADAMTS(L) superfamily shows different expression pattern between the five investigated ocular tissues, but also some members have differential expressions among the investigated age groups in same tissues.

Conclusion

Differential expression of ADAMTS(L) genes in ocular tissues from different age groups could explain some functional aspects of the tissues and also may be used as prognostic and diagnostic biomarkers for ocular diseases and pathologies. Further studies are required to explore their functional roles associated with ocular pathologies.

A health terminological system for inherited retinal diseases: Content coverage evaluation and a proposed classification

PURPOSE

To present a classification of inherited retinal diseases (IRDs) and evaluate its content coverage in comparison with common standard terminology systems.

METHODS

In this comparative cross-sectional study, a panel of subject matter experts annotated a list of IRDs based on a comprehensive review of the literature. Then, they leveraged clinical terminologies from various reference sets including Unified Medical Language System (UMLS), Online Mendelian Inheritance in Man (OMIM), International Classification of Diseases (ICD-11), Systematized Nomenclature of Medicine (SNOMED-CT) and Orphanet Rare Disease Ontology (ORDO).

RESULTS

Initially, we generated a hierarchical classification of 62 IRD diagnosis concepts in six categories. Subsequently, the classification was extended to 164 IRD diagnoses after adding concepts from various standard terminologies. Finally, 158 concepts were selected to be classified into six categories and genetic subtypes of 412 cases were added to the related concepts. UMLS has the greatest content coverage of 90.51% followed respectively by SNOMED-CT (83.54%), ORDO (81.01%), OMIM (60.76%), and ICD-11 (60.13%). There were 53 IRD concepts (33.54%) that were covered by all five investigated systems. However, 2.53% of the IRD concepts in our classification were not covered by any of the standard terminologies.

CONCLUSIONS

This comprehensive classification system was established to organize IRD diseases based on phenotypic and genotypic specifications. It could potentially be used for IRD clinical documentation purposes and could also be considered a preliminary step forward to developing a more robust standard ontology for IRDs or updating available standard terminologies. In comparison, the greatest content coverage of our proposed classification was related to the UMLS Metathesaurus.

Choroidal structure investigated by choroidal vascularity index in patients with inherited retinal diseases

PURPOSE

To evaluate the choroidal structure in patients with inherited retinal diseases (IRDs) by investigating the choroidal vascularity index (CVI).

METHODS

The present study was conducted on 113 IRD patients and 113 sex- and age-matched healthy individuals. Patients' data was extracted from the Iranian National Registry for IRDs (IRDReg®). Total choroidal area (TCA) was determined between retinal pigment epithelium and choroid-scleral junction,1500 microns on either side of the fovea. Luminal area (LA) was considered as the black area corresponding to the choroidal vascular spaces, following Niblack binarization. CVI was calculated as the ratio of the LA to the TCA. CVI and other parameters were compared among different types of IRD and the control group.

RESULTS

The IRD diagnosis included retinitis pigmentosa (n = 69), cone-rod dystrophy (n = 15), Usher syndrome (n = 15), Leber congenital amaurosis (n = 9), and Stargardt disease (n = 5). Sixty-one (54.0%) individuals of each of the study and control groups were male. The average CVI was 0.65 ± 0.06 in the IRD patients and 0.70 ± 0.06 in the control group (P < 0.001). Accordingly, the average of TCA and LA were 2.32 ± 0.63 and 1.52 ± 0.44 mm [1] in patients with IRDs, respectively. The measurements for the TCA and the LA were significantly lower in all subtypes of IRD (P-values < 0.05).

CONCLUSION

CVI is significantly lower in patients with IRD than in healthy age-matched individuals. Choroidal changes in IRDs may be related to the changes in the lumen of the choroidal vessels rather than the stromal changes.

The Inhibitory Effect of Connective Tissue Growth Factor Antibody on Postoperative Fibrosis in a Rabbit Model of Trabeculectomy

Purpose

To compare the efficacy of subconjunctival injection of an anti-connective tissue growth factor antibody (anti-CTGF) versus mitomycin-C (MMC) and placebo in reducing scar formation in a rabbit model of trabeculectomy.

Methods

A total of 14 rabbits were included. Nine rabbits underwent trabeculectomy with subconjunctival injections of either anti-CTGF antibody, MMC, or balanced salt solution (BSS), each administered in three eyes, before peritomy. The anti-CTGF group received a repeated dose of the antibody five days after surgery. All nine rabbits were euthanized on day 14; the globes were stained with hematoxylin & eosin, Masson's Trichrome, and immunohistochemistry for detecting alpha-smooth muscle (α-SMA) actin. RNA extraction was performed on five eyes of the remaining rabbits which included one eye without any surgery, one eye 5 hr after trabeculectomy without any injection, one eye five days after trabeculectomy without any injection, and two eyes five days after trabeculectomy with administration of MMC and BSS, respectively.

Results

The mean bleb area in the anti-CTGF, MMC, and control groups was 3.8 ± 1.45, 5.9 ± 1.4, and 3.5 ± 1.9 mm², respectively. Collagenous tissue was found to occupy the bleb area by 13.7%, 13.5%, and 18.5%, respectively. This ratio was significantly higher in the BSS group (P = 0.04). The expression of CTGF mRNA after 5 hr and five days in eyes undergoing trabeculectomy were significantly more pronounced as compared to the unoperated eye. The mean H-SCORE of α-SMA-immune reactive cells calculated as the grade of staining multiplied by the percentage of immune stained cells was 14.6, 10.22, and 140.58 in the anti-CTGF, MMC, and control groups, respectively. While the control eyes had a significantly higher score (Ps < 0.001), the anti-CTGF and MMC groups were comparable (P = 0.87).

Conclusion

Based on the results of this animal study, the anti-CTGF antibody injection resulted in a significant reduction in collagenous tissue and myofibroblast cells after trabeculectomy.

Augmented Expression of NOGO-A and Its Receptors in Human Retinal Pigment Epithelial Cells Following Treatment with Human Amniotic Fluid

Background:

Nogo-A, a myelin-associated inhibitor for neurite outgrowth, has important role in visual system development. Trans-differentiation ability of human amniotic fluid (HAF) on human retinal pigment epithelial cells (hRPEs) towards neural progenitor cells has been observed in several studies. We aimed to investigate the expression of NOGO-A gene and its receptors as a marker of neural differentiation in HAF-treated hRPE cells.

Methods:

hRPE cells were cultivated and immune characterized via RPE65 and cytokeratin 8/18 protein markers. Also, the cytotoxicity effect of 30% HAF on hRPE cells was evaluated using ELISA cell death assay. Finally, expression of NOGO-A and its receptors, RTN4R and LINGO1 was evaluated in the cells treated with HAF in comparison with FBS-treated cells using quantitative real-time PCR.

Results:

Harvested cells showed immunoreactivity for cytokeratin 8/18 and RPE65, confirming the hRPE cell identity. Besides, HAF had no cytotoxic effect on hRPE cells compared with FBS-treated cells. Results showed that NOGO-A and its receptors were expressed in cultured hRPE cells. Besides, comparative gene expression analysis revealed significant increased expression of the investigated genes in HAF-treated hRPE cells compared to FBS-treated cells.

Conclusion:

Augmented expression of NOGO-A and its receptors can support neural differentiation of hRPE when the cells are treated with HAF. Our outcomes provide more evidences on the trans-differentiation ability of HAF on hRPE cells into neural progenitors and retinal neural cells, but further studies are needed to elucidate the exact mechanism.

Genetic screening of TGFBI in Iranian patients with TGFBI-associated corneal dystrophies and a meta-analysis of global variation frequencies

PURPOSE

Transforming growth factor beta-induced (TGFBI)-associated corneal dystrophies (CDs) are a clinically heterogeneous group of CDs caused by mutations in the TGFBI gene. Nucleotide sequences encoding two arginine residues at positions 124 and 555 in TGFBI protein are mutation hotspots. We screened regions of TGFBI that include the hotspots in a cohort of Iranian patients with TGFBI-associated CDs. We also performed a meta-analysis for frequencies of all reported TGFBI mutations.

METHODS

Twenty-four TGFBI-associated CD-diagnosed patients were recruited. Exons 4 and 12 of TGFBI were amplified by the polymerase chain reaction and sequenced by Sanger protocol. A meta-analysis on reported TGFBI sequence data was done by reviewing all published relevant articles available in NCBI.

RESULTS

Twenty-two out of 24 patients had mutations in exons 4 or 12 of TGFBI. The most frequent mutations were p.Arg124Cys, p.Arg124His, and p.Arg555Trp; each of these was found in six families. Three other missense mutations including p.Arg555Gln, p.Ile522Asn, and p.Ala546Thr were also identified. The data suggested a fairly tight genotype/phenotype correlation for the most common CDs. Literature review evidenced that the reported mutations affected less than 30% of the amino acids of the TGFBI protein and that p.Arg124His, p.Arg124Cys, p.Arg555Trp, p.Arg124Leu, p.Arg555Gln, and p.His626Arg were the most frequent mutations.

CONCLUSION

TGFBI mutation profile of Iranian patients is very similar to that of the rest of the world. The meta-analysis confirmed the worldwide prevalence of p.Arg124 and p.Arg555, showed that p.His626Arg is also relatively frequent, and evidenced the value of screening exons 4 and 12 of TGFBI.

Identification of three novel homozygous variants in COL9A3 causing autosomal recessive Stickler syndrome

BACKGROUND

Stickler syndrome (STL) is a rare, clinically and molecularly heterogeneous connective tissue disorder. Pathogenic variants occurring in a variety of genes cause STL, mainly inherited in an autosomal dominant fashion. Autosomal recessive STL is ultra-rare with only four families with biallelic COL9A3 variants reported to date.

RESULTS

Here, we report three unrelated families clinically diagnosed with STL carrying different novel biallelic loss of function variants in COL9A3. Further, we have collected COL9A3 genotype-phenotype associations from the literature.

CONCLUSION

Our report substantially expands the molecular genetics and clinical basis of autosomal recessive STL and provides an overview about allelic COL9A3 disorders.

Mutation Screening of Six Exons of ABCA4 in Iranian Stargardt Disease Patients

Purpose

Stargardt disease type 1 (STGD1) is a recessively inherited retinal disorder that can cause severe visual impairment. ABCA4 mutations are the usual cause of STGD1. ABCA4 codes a transporter protein exclusively expressed in retinal photoreceptor cells. The genecontains 50 exons. Mutations are most frequent in exons 3, 6, 12, and 13, and exons 10 and 42 each contain two common variations. We aimed to screen these exons for mutations in Iranian STGD1 patients.

Methods

Eighteen STGD1 patients were recruited for genetic analysis. Diagnosis by retina specialists was based on standard criteria, including accumulation of lipofuscin. The six ABCA4 exons were PCR amplified and sequenced by the Sanger method.

Results

One or more ABCA4-mutated alleles were identified in 5 of the 18 patients (27.8%). Five different mutations including two splice site (c.1356+1G>A and c.5836-2A>G) and three missense mutations (p.Gly1961Glu, p.Gly1961Arg, and p.Gly550Arg) were found. The p.Gly1961Glu mutation was the only mutation observed in two patients.

Conclusion

As ABCA4 mutations in exons 6, 12, 10, and 42 were identified in approximately 25% of the patients studied, these may be appropriate exons for screening projects. As in other populations, STDG1 causative ABCA4 mutations are heterogeneous among Iranian patients, and p.Gly1961Glu may be relatively frequent.

Carrier Status for p.Gly61Glu and p.Arg368His CYP1B1 Mutations Causing Primary Congenital Glaucoma in Iran

Purpose

To estimate carrier frequencies of CYP1B1 mutations p.Gly61Glu and p.Arg368His, respectively, in Talesh and the east of Guilan province in Iran with a maximum error of 2%. Previously, it was shown that these CYP1B1 mutations may be relatively prevalent in these regions.

Methods

Population-based screenings were performed. DNA was extracted from saliva samples of 1036 individuals from Talesh and 3029 individuals from the east of Guilan. P.Gly61Glu and p.Arg368His screenings were performed, respectively, by RFLP and ARMS-based PCR protocols. For confirmation, the DNA of individuals with mutations was sequenced using the Sanger protocol.

Results

Nine individuals from Talesh (0.86%; 95%CI: 0.45–1.64%) carried the p.Gly61Glu mutation, and 73 from the east of Guilan (2.41%; 95%CI: 1.91–3.04%) carried p.Arg368His. There was no significant difference in frequencies between urban and rural regions of the various cities, nor among four cities within the east of Guilan.

Conclusion

The frequencies of p.Gly61Glu carriers in Talesh and of p.Arg368His carriers in the east of Guilan were within the 95% confidence interval of a previous study based on screenings of fewer individuals. The reliability of the recent estimates is higher, as the confidence interval for p.Gly61Glu decreased from 6.5% to 1.19% and the interval for p.Arg368His decreased from 4% to 1.13%. Based on the new findings, the maximum expected frequency of p.Gly61Glu carriers in Talesh is 1.64%, and of p.Arg368His carriers in the east of Guilan is 3%. The need for performing premarital screenings in the respective cities can be evaluated.

Variable Expressivity of Wolfram Syndrome in a Family with Multiple Affected Subjects

Purpose

To study the genetic basis and clinical manifestations of Wolfram syndrome in a multi-affected family.

Methods

Complete clinical examinations including urological, ophthalmic, neurological, and endocrinologic assessment were performed for three affected family members. Genomic DNA was extracted from peripheral blood leukocytes with salting out method and all WFS1 exons and their flanking regions were sequenced. Candidate variation was screened for segregation in the pedigree by Sanger sequencing.

Results

A known pathogenic missense mutation in WFS1 gene (c.1885C>T which leads to p.Arg629Trp in the encoded protein) was identified in all affected individuals. Both clinical and genetic investigations confirmed Wolfram syndrome diagnosis with variable phenotypic features

Conclusion

Identical mutations in the Wolfram syndrome causative gene can lead to variable manifestations of the syndrome even in the same family. Although the medical findings and clinical examination are imperative for the diagnosis of Wolfram syndrome, genetic testing is useful to confirm the diagnosis, especially in cases with possible reduced penetrance of the characteristic signs.

Prenatal diagnosis of primary congenital glaucoma and histopathological features in a fetal globe with cytochrome p4501B1 mutations

BACKGROUND/OBJECTIVES

This study aims to report the developmental and histopathological features of ocular tissues from an electively aborted human fetus with mutations in cytochrome p4501B1, and thus predisposed to primary congenital glaucoma in comparison to an age-matched healthy fetal globe.

SUBJECTS/METHODS

Both eyes of two 17-week gestational aged fetuses, the first with CYP1B1 mutations and the second as healthy control fetus, were studied. Hematoxylin and eosin, Periodic acid-Schiff, Gomori's trichrome, and Verhoeff-Van Gieson staining protocols in addition to immunohistochemistry staining using anti-cytochrome p4501B1, anti-fibrillin-1, and anti-4-hydroxy-2-nonenal antibodies, as primary antibodies, were performed to assess the effect of the mutations on tissue development, cytochrome p4501B1 protein expression, extracellular matrix structure, and oxidative stress in the developing fetus eye. Quantitative analyses were performed using ImageJ software. Student's t-test was used for statistical analysis and P-values <0.05 were considered as significant.

RESULTS

Delayed development in ocular tissues, decreased expression of cytochrome p4501B1 protein, irregular extracellular matrix structure, and increased oxidative stress biomarker were evident in the ocular tissues of the fetus with cytochrome p4501B1 mutations as compared to a normal globe from an age-matched fetus.

CONCLUSION

To the best of our knowledge, this is the first report of prenatal diagnosis of primary congenital glaucoma. We also describe histopathological changes in the primary congenital glaucoma-affected globes revealing the effect of cytochrome p4501B1 deficiency on ocular tissues during early fetal development contributing to the glaucoma phenotype.

Retinal Vascular Abnormalities in Different Types of Inherited Retinal Dystrophies Assessed by Optical Coherence Tomography Angiography

Purpose:

To investigate the retinal vascular characteristics among patients with different types of inherited retinal dystrophies (IRDs).

Methods:

This comparative cross-sectional study was conducted on 59 genetically confirmed cases of IRD including 37 patients with retinitis pigmentosa (RP) (74 eyes), 13 patients with Stargardt disease (STGD) (26 eyes), and 9 patients with cone-rod dystrophy (CRD) (18 eyes). Both eyes of 50 age- and sex-matched healthy individuals were investigated as controls. All participants underwent optical coherence tomography angiography to investigate the vascular densities (VDs) of superficial and deep capillary plexus (SCP and DCP) as well as foveal avascular zone area.

Results:

In RP, significantly lower VD in whole image (P = 0.001 for DCP), fovea (P = 0.038 for SCP), parafovea (P < 0.001 for SCP and DCP), and perifovea (P < 0.001 for SCP and DCP) was observed compared to controls. In STGD, VD of parafovea (P = 0.012 for SCP and P = 0.001 for DCP) and fovea (P = 0.016 for DCP) was significantly lower than controls. In CRD, the VD of parafovea (P = 0.025 for DCP) was significantly lower than controls. Whole image density was significantly lower in RP compared to STGD (P < 0.001 for SCP) and CRD (P = 0.037 for SCP). VD in parafovea (P = 0.005 for SCP) and perifovea (P < 0.001 for SCP and DCP) regions was significantly lower in RP compared with STGD. Also, foveal VD in STGD was significantly lower than RP (P = 0.023 for DCP).

Conclusion:

Our study demonstrated lower VDs in three different IRDs including RP, STGD, and CRD compared to healthy controls. Changes were more dominant in RP patients.

Intravitreal connective tissue growth factor neutralizing antibody or bevacizumab alone or in combination for prevention of proliferative vitreoretinopathy in an experimental model

Connective tissue growth factor (CTGF) is released by retinal pigment epithelial (RPE) cells and detectable in proliferative membranes (PrMs). This experimental study was performed to investigate the mRNA and protein levels of both CTGF and vascular endothelial growth factor A (VEGF-A) in a rabbit model of proliferative vitreoretinopathy (PVR). In addition, the effects of a single intravitreal injection of the safe dose of anti-CTGF or bevacizumab as monotherapy and in combination were evaluated. PVR was induced in the right eye of albino rabbits by intravitreal injection of cultured adult human RPE cells. Quantitative real-time reverse transcription PCR (qRT-PCR) and Western blot analysis of CTGF and VEGF-A were performed on whole eye tissue in the PVR model versus controls at different time points. In the next step, the PVR models were assigned to five groups. The monotherapy groups received a single intravitreal injection of 0.1 ml of anti-CTGF 100 μg/ml (final concentration of 6.6 μg/ml in the vitreous) or 0.03 ml of 25 mg/ml bevacizumab. In the combined group, the abovementioned amounts of anti-CTGF and bevacizumab were injected intravitreally from separate sites in one session. No antibody injection was performed in the control group. Intravitreal injection of 0.1 ml of control IgG (1 mg/ml of isotype matched) antibody was performed in the placebo group. After 2 weeks, histologic evaluation including, trichrome staining for collagen, immunostaining by anti-alpha-smooth muscle actin for myofibroblasts, and anti-collagen type-1 antibody on paraffin embedded anterior-posterior sections was done. In addition, fundus photography was performed for clinically equivalent PVR staging. Twenty-four hours following PVR induction, CTGF mRNA and protein levels increased five- and- three-fold compared to controls, respectively (P < 0.001). VEGF-A mRNA and protein levels decreased significantly after 72 h of PVR induction compared to controls (P < 0.05). Means of PrM thickness and myofibroblast cell counts significantly decreased in the anti-CTGF group (P < 0.001 and P < 0.05, respectively). The mean area of collagen type-1 fibers of PrM in the mono- and combination therapy groups that received intravitreal anti-CTGF was significantly reduced (P < 0.001); in addition, mild PVR (stage-1 and 2) formation occurred in comparison with moderate to severe PVR (stage-4 and higher) in other groups. In conclusion, we found that intravitreal injection of CTGF neutralizing antibody resulted in a reduction in PrM thickness, collagen fibers and myofibroblast density in the PVR model. CTGF inhibition may represent a potential therapeutic target for PVR.

SVEP1 as a Genetic Modifier of TEK-Related Primary Congenital Glaucoma

Purpose

Affecting children by age 3, primary congenital glaucoma (PCG) can cause debilitating vision loss by the developmental impairment of aqueous drainage resulting in high intraocular pressure (IOP), globe enlargement, and optic neuropathy. TEK haploinsufficiency accounts for 5% of PCG in diverse populations, with low penetrance explained by variable dysgenesis of Schlemm's canal (SC) in mice. We report eight families with TEK-related PCG, and provide evidence for SVEP1 as a disease modifier in family 8 with a higher penetrance and severity.

Methods

Exome sequencing identified coding/splice site variants with an allele frequency less than 0.0001 (gnomAD). TEK variant effects were assayed in construct-transfected HEK293 cells via detection of autophosphorylated (active) TEK protein. An enucleated eye from an affected member of family 8 was examined via histology. SVEP1 expression in developing outflow tissues was detected by immunofluorescent staining of 7-day mouse anterior segments. SVEP1 stimulation of TEK expression in human umbilical vascular endothelial cells (HUVECs) was measured by TaqMan quantitative PCR.

Results

Heterozygous TEK loss-of-function alleles were identified in eight PCG families, with parent–child disease transmission observed in two pedigrees. Family 8 exhibited greater disease penetrance and severity, histology revealed absence of SC in one eye, and SVEP1:p.R997C was identified in four of the five affected individuals. During SC development, SVEP1 is secreted by surrounding tissues. SVEP1:p.R997C abrogates stimulation of TEK expression by HUVECs.

Conclusions

We provide further evidence for PCG caused by TEK haploinsufficiency, affirm autosomal dominant inheritance in two pedigrees, and propose SVEP1 as a modifier of TEK expression during SC development, affecting disease penetrance and severity.

Choroidal Thickness in Different Types of Inherited Retinal Dystrophies

Purpose

To compare the choroidal thickness among eyes with retinitis pigmentosa (RP), Stargardt disease, Usher syndrome, cone-rod dystrophy, and healthy eyes of sex- and age-matched individuals.

Methods

In this comparative study, 503 eyes with RP (n = 264), cone-rod dystrophy (n = 109), Stargardt disease (n = 76), and Usher syndrome (n = 54) were included. To validate the data, 109 healthy eyes of 56 sex- and age-matched individuals were studied as controls. Choroidal imaging was performed using enhanced depth imaging-optical coherence tomography. Choroidal thickness was measured manually using MATLAB software at 13 points in nasal and temporal directions from the foveal center with the interval of 500 µm and the choroidal area encompassing the measured points was calculated automatically.

Results

The mean age was 36.33 ± 13.07 years (range, 5 to 72 years). The mean choroidal thickness at 13 points of the control eyes was statistically significantly higher than that in eyes with RP (P < 0.001) and Usher syndrome (P< 0.05), but not significantly different from that in eyes with Stargardt disease and cone-rod dystrophy. Among different inherited retinal dystrophies (IRDs), the choroidal thickness was the lowest in eyes with RP (P < 0.001). Choroidal thickness in the subfoveal area correlated negatively with best-corrected visual acuity (r = -0.264, P < 0.001) and the duration of ocular symptoms (r = -0.341, P < 0.001) in all studied IRDs. No significant correlation was observed between the subfoveal choroidal thickness and central macular thickness (r = -0.24, P = 0.576).

Conclusion

Choroidal thinning in four different types of IRDs does not follow a similar pattern and depends on the type of IRD and the duration of ocular symptoms. A larger cohort is required to verify these findings

Association of Saitohin gene rs62063857 polymorphism with dry type age-related macular degeneration

PURPOSE

Age-related macular degeneration (AMD) as the leading cause of central visual loss in the developed countries has extensive pathologic similarities with Alzheimer's disease (AD). Saitohin rs62063857 Q7 R polymorphism is associated with increased risk of AD though we decided to evaluate the possible association of this polymorphism with advanced AMD.

MATERIALS AND METHODS

152 advanced AMD patients (134 wet AMD and 18 geographic atrophy) and 75 healthy controls included in this study. Cases and controls went through a standard ophthalmologic examination by a retinal specialist. Saitohin gene rs62063857 polymorphism determined by using PCR technique and restriction enzyme HinFI. To evaluate the differences between groups we used t-test, Chi-Squared and one-tailed Fisher exact test.

RESULTS

Distribution of genotypes was not significantly different between total AMD or wet AMD patients compared to that of controls (total AMD RR+QR: OR = 1.51, CI = 0.82-2.79, P = .12; wet AMD RR+QR: OR = 1.39, CI = 0.74-2.59, P = .19). The RR+QR genotypes were significantly higher in dry AMD group compared to that of controls (RR+QR: OR = 2.75, CI = 0.96-7.9, P = .05).

CONCLUSION

Our results showed that although STH Q7 R polymorphism was not associated with wet AMD susceptibility it was significantly associated with geographic atrophy.

The First Inherited Retinal Disease Registry in Iran: Research Protocol and Results of a Pilot Study

BACKGROUND

To describe the protocol for developing a national inherited retinal disease (IRD) registry in Iran and present its initial report.

METHODS

This community-based participatory research was approved by the Ministry of Health and Medical Education of Iran in 2016. To provide the minimum data set (MDS), several focus group meetings were held. The final MDS was handed over to an engineering team to develop a web-based software. In the pilot phase, the software was set up in two referral centers in Iran. Final IRD diagnosis was made based on clinical manifestations and genetic findings. Ultimately, patient registration was done based on all clinical and non-clinical manifestations.

RESULTS

Initially, a total of 151 data elements were approved with Delphi technique. The registry software went live at www. IRDReg.org based on DHIS2 open source license agreement since February 2016. So far, a total of 1001 patients have been registered with a mean age of 32.41±15.60 years (range, 3 months to 74 years). The majority of the registered patients had retinitis pigmentosa (42%, 95% CI: 38.9% to 45%). Genetic testing was done for approximately 20% of the registered individuals.

CONCLUSION

Our study shows successful web-based software design and data collection as a proof of concept for the first IRD registry in Iran. Multicenter integration of the IRD registry in medical centers throughout the country is well underway as planned. These data will assist researchers to rapidly access information about the distribution and genetic patterns of this disease.

PRPH2 mutation as the cause of various clinical manifestations in a family affected with inherited retinal dystrophy

Background/Objectives: To reveal the underlying genetic defect in a complex family affected with different clinical features of inherited retinal dystrophy, we carried out whole exome sequencing followed by confirmatory molecular tests.Materials and Methods: Complete ophthalmic examinations were performed for available affected family members. Whole exome sequencing, bioinformatics analysis, Sanger sequencing confirmation, and segregation analysis were done to identify the causative mutation.Results: Clinical findings suggested fundus flavimaculatus as an early clinical feature progressing to an extensive chorioretinal atrophy involving the macula and mid-periphery of the fundus in one parent and central areolar chorioretinal dystrophy (CACD) as the most probable clinical diagnosis in another parent. Macular pattern dystrophy for one of their daughters and a Leber congenital amaurosis (LCA) like phenotype for the daughter with an early onset retinal dystrophy (EORD) phenotype was suggested. We found a known pathogenic nonsense variation in the PRPH2 gene (NM_000322: p.Gln239Ter). The parents with end stage fundus flavimaculatus and CACD diagnosis and their daughter with macular pattern dystrophy were heterozygous for the identified variant. The daughter affected with EORD/LCA like retinal dystrophy was homozygous for the same variation.Conclusions: In this family, the same pathogenic variant in PRPH2 gene showed a wide range of clinical features of extensive chorioretinal macular atrophy with flecks as fundus falvimaculatus to CACD and macular pattern dystrophy in the heterozygous inheritance pattern and early onset/LCA like retinal dystrophy in the patient who was homozygous for the causative variant.

Incomplete penetrance of CRX gene for autosomal dominant form of cone-rod dystrophy

Purpose: Cone-rod dystrophy (CRD) is an inherited retinal dystrophy that is transmitted via different modes of inheritance. Mutations in more than 30 genes have been identified to cause the disease. We aimed to investigate the genetic agents of two unrelated cone-rod dystrophy affected Iranian families with autosomal recessive inheritance patterns. Methods: Whole-exome sequencing (WES) was performed for identification of the disease-causing mutations in the probands of both families. The candidate mutations were further confirmed by Sanger sequencing. Samples from five available members of each family were then sequenced for the mutations present in the probands. Comprehensive ocular examinations for all members of the families carrying the mutations were completed by ophthalmologists. Results: We identified a novel premature stop codon c.310C>T in CRX gene in heterozygote form in two symptomatic and two non-symptomatic members of one family (family-A), and a known CRX mutation c.122G>A in homozygote form in another (family B). c.122G>A has been reported to cause late-onset autosomal dominant form of the disease in previous studies. However, the middle-aged heterozygous carriers of the mutation in this family showed normal phenotype. Conclusion: The CRX gene has been previously linked to the autosomal dominant form of cone-rod dystrophy. We report incomplete penetrance of CRX gene for autosomal dominant form of the disease. Incomplete penetrance of the mutations may be partly caused by the influence of other genes in the complex genetic network underlying retinal regulation.

COL18A1 is a candidate eye iridocorneal angle-closure gene in humans

Primary angle-closure glaucoma (PACG) is a common form of glaucoma in the Far East. Its defining feature is iridocorneal angle closure. In addition to PACG, indications of angle closure are included in the diagnostic criteria of related conditions primary angle-closure suspect (PACS) and primary angle closure (PAC). To the best of our knowledge, a causative gene for iridocorneal angle closure in humans has not been identified. This study aimed to identify the genetic cause of iridocorneal angle closure in a pedigree with at least 10 individuals diagnosed with PACS, PAC or PACG. Results of linkage analysis, segregation analysis of 44 novel variations, whole exome sequencing of 10 individuals, screenings of controls and bioinformatics predictions identified a mutation in COL18A1 that encodes collagen type XVIII as the most likely cause of angle closure in the pedigree. The role of COL18A1 in the etiology of Knobloch syndrome (KS) that is consistently accompanied by optic anomalies, available functional data on the encoded protein and the recognized role of collagens and the extracellular matrix in glaucoma pathogenesis supported the proposed role of the COL18A1 mutation in the pedigree. Subsequent identification of other COL18A1 mutations in PACS affected individuals of two unrelated families further supported that COL18A1 may affect angle closure. These PACS individuals were parents and grandparents of KS-affected children. In conclusion, a gene that affects angle closure in humans, a critical feature of PACG, has been identified. The findings also reinforce the importance of collagens in eye features and functions.

P.Gly61Glu and P.Arg368His Mutations in CYP1B1 that Cause Congenital Glaucoma may be Relatively Frequent in Certain Regions of Gilan Province, Iran

PURPOSE

To perform a population-based screening of four CYP1B1 mutations-p.Gly61Glu, p.Arg368His, p.Arg390His, and p.Arg469Trp-in the province of Gilan, Iran. Previous studies have shown that CYP1B1 is a cause of disease in approximately 70% of Iranian patients with primary congenital glaucoma (PCG), and that these four mutations constitute the majority of CYP1B1 mutated alleles. The carrier frequencies may even justify premarital screenings.

METHODS

DNA was extracted from the blood samples of 700 individuals recruited in a population-based epidemiology study in Gilan. Screenings were performed using polymerase chain reaction protocols based on restriction fragment length polymorphism or the amplification-refractory mutation system. For confirmation, the DNA of individuals with mutations was sequenced using the Sanger protocol.

RESULTS

Five individuals carried the p.Gly61Glu mutation, and seven carried the p.Arg368His mutation. The p.Arg390His and p.Arg469Trp mutations were not observed in any of the 700 individuals screened. The mutations were not geographically randomly distributed in Gilan; four of the p.Gly61Glu-harboring individuals were from Talesh, and six of the p.Arg368His-harboring individuals were from the eastern regions of Gilan.

CONCLUSION

The frequency of individuals who carry either p.Gly61Glu or p.Arg368His is relatively high in Gilan, and notably high in certain localities within Gilan. We suggest further screenings be performed to definitively assess the need for implementing measures to encourage screening for p.Gly61Glu and p.Arg368His before marriage in Talesh and the eastern regions of Gilan, respectively. Finally, our assessment showed that regional frequencies of CYP1B1 mutations do not necessarily mirror national frequencies.

LTBP2 knockdown and oxidative stress affect glaucoma features including TGFβ pathways, ECM genes expression and apoptosis in trabecular meshwork cells

Glaucoma is the leading cause of irreversible blindness worldwide. Although the etiology of glaucoma is incompletely understood, it is known that the extracellular matrix (ECM) of the trabecular meshwork, oxidative stress, TGFβ signaling pathways, and apoptosis are important components of glaucoma pathogenesis. These components appear to be interrelated, but knowledge on their interactions remains incomplete. Relevant to this gap in knowledge, LTBP2, glaucoma causing gene, may also be related to the mentioned components of glaucoma pathogenesis because of its putative roles in TGFβ signaling and ECM functions. This background prompted us to further query interactions among some molecules and pathways thought to be important in glaucoma etiology, with emphasis on oxidative stress and LTBP2. To this end, effects of LTBP2 siRNA knockdown, oxidative stress induction, TGFβ2 and gremlin exposures on canonical TGFβ and BMP signaling pathways, expression of ECM related genes, and apoptosis were assayed in primary human trabecular meshwork cell cultures. We found that oxidative stress induction and LTBP2 knockdown both affected all the processes queried, and that their affects paralleled one another. We suggest that effects of both oxidative stress and LTBP2 knockdown on the ECM and apoptosis may be mediated by TGFβ and BMP signaling pathway activation.

The p.Gly61Glu Mutation in CYP1B1 Affects the Extracellular Matrix in Glaucoma Patients

PURPOSE

The aim of this work was to assess the possible effects of CYP1B1 mutations on the extracellular matrix (ECM) in glaucoma patients. CYP1B1 mutations are the cause of disease in a notable fraction of primary congenital glaucoma (PCG) patients and in a smaller fraction of primary open angle glaucoma (POAG) patients.

METHODS

The study was performed on a glaucoma family with the common homozygous p.Gly61Glu CYP1B1 mutation. The father was affected with POAG and three siblings had PCG. Microscopy was performed on the skin of the father and one son, as well as controls. Immunohistochemical studies were done using anti-CYP1B1 and anti-fibrillin-1 antibodies. Fibrillin-1 served as a marker for the ECM, and electron microscopy was also performed.

RESULTS

CYP1B1 expression patterns were the same in the patients and controls. However, microfibrils that are associated with fibrillin-1 were less abundant and more fragmented in both patients. Electron microscopy showed disturbed collagen fibers only in the PCG patient.

CONCLUSIONS

The p.Gly61Glu mutation in CYP1B1 affects the ECM structure. This implies that the ECM of the trabecular meshwork may also be disrupted in a manner that affects aqueous humor flow resulting in increased intraocular pressure and contributing to the glaucoma phenotype.

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.

Contribution of the latent transforming growth factor-β binding protein 2 gene to etiology of primary open angle glaucoma and pseudoexfoliation syndrome

PURPOSE

To assess for the first time the possible contribution of latent transforming growth factor (TGF)-beta binding protein 2 (LTBP2), an extracellular matrix (ECM) protein that associates with fibrillin-1-containing microfibrils, to the etiology of primary open angle glaucoma (POAG) and pseudoexfoliation (PEX) syndrome. Mutations in LTBP2 have previously been shown to be the cause of primary congenital glaucoma (PCG) and other disorders that often manifest as secondary glaucoma.

METHODS

All exons of LTBP2 were sequenced in the DNA of 42 unrelated patients with POAG and 48 unrelated patients with PEX syndrome. Contribution of candidate variations to disease was assessed by screening in control individuals and use of biochemical, bioinformatics, and evolutionary criteria, and in one case by segregation analysis within the family of a proband with POAG. Microscopy was performed on the skin of a patient with PEX syndrome whose condition developed into PEX glaucoma during the course of the study and on the skin of her son previously identified with PCG who harbored the same LTBP2 mutation.

RESULTS

Among the 30 sequence variations observed in LTBP2, five found in five patients with POAG and two found in two patients with PEX glaucoma syndrome may contribute to their diseases. One of the mutations was observed in a patient with POAG and in a patient with PEX glaucoma syndrome. Light, fluorescent, and electron microscopy showed that a mutation present in one of the individuals affected with PEX glaucoma syndrome and in her son affected with PCG causes disruptions in the ECM.

CONCLUSIONS

Some LTBP2 sequence variations can contribute to the etiology of POAG and PEX glaucoma syndrome. It is not expected that in these diseases LTBP2 mutations behave in a strictly Mendelian fashion with complete penetrance. In conjunction with recent findings, the results suggest that anomalies in the ECM are among the factors that can contribute to POAG and PEX glaucoma syndrome. LTBP2 and other related ECM protein coding genes should be screened in larger cohorts with these diseases, which are common disorders and important to the public health.

Myocilin mutations are not a major cause of primary congenital glaucoma in Iranian patients

PURPOSE

To assess the frequency of mutations in the Myocilin (MYOC) gene in Iranian patients affected with primary congenital glaucoma (PCG).

METHODS

The individuals evaluated herein are among a larger cohort of 100 patients who had previously been screened for CYP1B1 mutations. Eighty subjects carried mutations in CYP1B1, but the remaining 20 patients who did not, underwent screening for MYOC mutations for the purpose of the study. MYOC exons in the DNA were polymerase chain reaction (PCR) amplified and sequenced. Sequencing was performed using PCR primers, the ABI big dye chemistry and an ABI3730XL instrument. Sequences were analyzed by comparing them to reference MYOC sequences using the Sequencher software.

RESULTS

Four MYOC sequence variations were observed among the patients, but none of them were considered to be associated with disease status. Three of these variations were single nucleotide polymorphisms already reported not to be disease causing, the fourth variation created a synonymous codon and did not affect any amino acid change.

CONCLUSION

In this cohort, MYOC mutations were not observed in any Iranian subject with PCG. It is possible that in a larger sample, a few subjects carrying disease causing MYOC mutations could have been observed. But our results show that the contribution of MYOC to PCG status in Iran is small if any.

Variable expressivity and high penetrance of CYP1B1 mutations associated with primary congenital glaucoma

OBJECTIVE

To investigate penetrance and expressivity of CYP1B1 genotypes associated with primary congenital glaucoma (PCG).

DESIGN

Observational case series, systematic review, and comparative analysis of the literature.

PARTICIPANTS

Forty probands affected with PCG, 16 siblings affected with PCG, and 103 siblings and 75 parents of the probands reported not to be affected by history. The participants were members of 40 unrelated families.

METHODS

Mutations were screened by restriction fragment length polymorphism, allele-specific polymerase chain reaction amplification, and direct sequencing. Ophthalmologic examination included slit-lamp biomicroscopy, intraocular pressure (IOP) measurement, gonioscopy, and high magnification stereoscopic fundus examination, followed by standard achromatic perimetry.

MAIN OUTCOME MEASURES

Identification of subjects carrying CYP1B1 mutations. Glaucoma diagnosis based on slit-lamp examination, IOP measurement, gonioscopic findings, optic nerve appearance, and perimetry.

RESULTS

Fifteen different homozygous or compound heterozygous mutant CYP1B1 genotypes were identified. Most probands and previously diagnosed subjects harbored G61E, R368H, R390H, and R469W mutations. Among the 178 apparently unaffected family members, 20 subjects from 12 families were observed to harbor 2 CYP1B1 mutations, suggesting an average penetrance of 73% for all the mutations. These 20 subjects ranged in age from 14 to 54 years. R390H appeared to have a notably high penetrance. Penetrance was 50% in the subset of families with incomplete penetrance. Ophthalmologic examination on 14 of the 20 apparently nonpenetrant individuals showed that 8 subjects were affected with juvenile open-angle glaucoma (JOAG) or primary open-angle glaucoma (POAG), and that 3 subjects were glaucoma suspect. One of the individuals with a JOAG diagnosis was the identical twin sibling of a proband affected with PCG.

CONCLUSIONS

At least 57% of the PCG nonpenetrant individuals examined clinically were affected with JOAG or POAG to varying degrees, and overall penetrance of "affected CYP1B1 genotypes" with respect to glaucoma may be more than 90%. These findings suggest that "affected CYP1B1 genotypes" exhibit variable expressivity rather than nonpenetrance. The clinical implication of this observation is that seemingly unaffected relatives of patients with PCG, particularly those known to harbor CYP1B1 mutations, should undergo regular ophthalmologic examination to allow early diagnosis.

Loss of function mutations in the gene encoding latent transforming growth factor beta binding protein 2, LTBP2, cause primary congenital glaucoma

Glaucoma is a heterogeneous group of optic neuropathies that manifests by optic nerve head cupping or degeneration of the optic nerve, resulting in a specific pattern of visual field loss. Glaucoma leads to blindness if left untreated, and is considered the second leading cause of blindness worldwide. The subgroup primary congenital glaucoma (PCG) is characterized by an anatomical defect in the trabecular meshwork, and age at onset in the neonatal or infantile period. It is the most severe form of glaucoma. CYP1B1 was the first gene genetically linked to PCG, and CYP1B1 mutations are the cause of disease in 20-100% of patients in different populations. Here, we report that LTBP2 encoding latent transforming growth factor beta binding protein 2 is a PCG causing gene, confirming results recently reported. A disease-associated locus on chromosome 14 was identified by performing whole genome autozygosity mapping in Iranian PCG families using high density single nucleotide polymorphism chips, and two disease-segregating loss of function mutations in LTBP2, p.Ser472fsX3 and p.Tyr1793fsX55, were observed in two families while sequencing candidate genes in the locus. The p.Tyr1793fsX55 mutation affects an amino acid close to the C-terminal of the encoded protein. Subsequently, LTBP2 expression was shown in human eyes, including the trabecular meshwork and ciliary processes that are thought to be relevant to the etiology of PCG.

Sex Bias in Primary Congenital Glaucoma Patients with and without CYP1B1 Mutations

PURPOSE

To investigate variations in sex ratio among Iranian primary congenital glaucoma (PCG) patients with and without mutations in the CYP1B1 gene and to evaluate possible clinical variations associated with sex in these two groups.

METHODS

Phenotypical data on 104 unrelated Iranian PCG patients who had previously been screened for CYP1B1 mutations were analyzed. Emphasis was placed on analysis of sex ratios among patients with and without CYP1B1 mutations. In addition to sex, familial and sporadic incidence and clinical features including age at onset, bilateral/unilateral involvement, corneal diameter, intraocular pressure, and cup-disc ratios were compared between these two groups. Information on phenotypical parameters was available for most but not all patients.

RESULTS

Among the 93 PCG patients whose sex was recorded, 57 were male (61.3%) and 36 were female (38.7%) (P=0.03). Patients with CYP1B1 mutations included 37 male (66.1%) and 29 female (43.9%) subjects (P=0.30), while patients without the mutation included 20 (74.1%) male and 7 (25.9%) female individuals (P=0.013). Our data did not provide conclusive evidence on difference in severity of the disease between those with and without CYP1B1 mutations, nor between the two sexes.

CONCLUSION

Consistent with data on PCG patients from other populations, the overall incidence of PCG in Iran seems to be higher among male subjects. The difference in incidence between the two sexes was not significant among patients whose disease was due to mutations in CYP1B1. The overall higher incidence of PCG among male subjects seems to be attributable to a higher incidence in male patients not harboring CYP1B1 mutations, suggesting that other genes or factors may be involved in manifestation of PCG phenotypes in a sex dependent manner.

Screening of common CYP1B1 mutations in Iranian POAG patients using a microarray-based PrASE protocol

PURPOSE

The gene coding cytochrome P4501B1 (CYP1B1) has been shown to be a major cause of primary congenital glaucoma in the Iranian population. More recently it was shown to also be important in juvenile-onset open angle glaucoma (JOAG). We aimed to further investigate the role of CYP1B1 in a larger cohort of primary open angle glaucoma (POAG) patients which included late-onset patients. We also aimed to set up a microarray based protocol for mutation screening with an intent of using the protocol in a future population level screening program.

METHODS

Sixty three POAG patients, nine affected family members, and thirty three previously genotyped primary congenital glaucoma (PCG) patients were included in the study. Clinical examination included slit lamp biomicroscopy, IOP measurement, gonioscopic evaluation, fundus examination, and measurement of perimetry. G61E, R368H, R390H, and R469W were screened by a protocol that included multiplexed allele specific amplification in the presence of a protease (PrASE), use of sequence tagged primers, and hybridization to generic arrays on microarray slides. The entire coding sequences of CYP1B1 and myocilin (MYOC) genes were sequenced in all individuals assessed by the microarray assay to carry a mutation. Intragenic single nucleotide polymorphism (SNP) haplotpes were determined for mutated alleles.

RESULTS

Genotypes assessed by the array-based PrASE methodology were in 100% concordance with sequencing results. Seven mutation carrying POAG patients (11.1%) were identified, and their distribution was quite skewed between the juvenile-onset individuals (5/21) as compared to late-onset cases (2/42). Four of the seven mutation carrying Iranian patients harbored two mutated alleles. CYP1B1 mutated alleles in Iranian PCG and POAG patients shared common haplotypes. MYOC mutations were not observed in any of the patients.

CONCLUSIONS

The PrASE approach allowed reliable simultaneous genotyping of many individuals. It can be an appropriate tool for screening common mutations in large sample sizes. The results suggest that CYP1B1 is implicated in POAG among Iranians, notably in the juvenile-onset form. Contrary to POAG patients studied in other populations, many mutation harboring Iranian patients carry two mutated alleles. We propose an explanation for this observation.

Contributions of MYOC and CYP1B1 mutations to JOAG

PURPOSE

To investigate the role of MYOC and CYP1B1 in Iranian juvenile open angle glaucoma (JOAG) patients.

METHODS

Twenty-three JOAG probands, their available affected and unaffected family members, and 100 ethnically matched control individuals without history of ocular disease were recruited. Clinical examinations of the probands included slit lamp biomicroscopy, intraocular pressure (IOP) measurement, gonioscopic evaluation, fundus examination, and perimetry measurement. Familial cases were classified according to the mode of inheritance. Exons of MYOC and CYP1B1 were sequenced, and novel variations assessed in the control individuals. Potential disease-associated variations were tested for segregation with disease status in available family members.

RESULTS

The mode of inheritance of the disease in the families of four probands (17.4%) appeared to be autosomal dominant and in at least eight (34.8%) to be autosomal recessive. Four patients carried MYOC mutations, and an equal number carried CYP1B1 mutations. The MYOC mutations were heterozygous; two of them (p.C8X and p.L334P) are novel, and one codes for the shortest truncated protein so far reported. Autosomal recessive inheritance was consistent with inheritance observed in families of patients carrying CYP1B1 mutations. All these patients carried homozygous mutations.

CONCLUSIONS

MYOC and CYP1B1 contributed equally to the disease status of the Iranian JOAG patients studied. The contribution of the two genes appeared to be independent in that no patient carried mutations in both genes. The fraction of Iranian patients carrying MYOC mutations was comparable to previously reported populations.