Outcomes of the Aurolab aqueous drainage implant and trabeculectomy with mitomycin C in iridocorneal endothelial syndrome.

PURPOSE: To compare the surgical outcomes of the Aurolab aqueous drainage implant (AADI) and trabeculectomy with mitomycin C (MMC) in patients with glaucoma secondary to iridocorneal endothelial (ICE) syndrome. MATERIALS AND METHODS: This retrospective comparative case series included 41 eyes of 41 patients with ICE syndrome and glaucoma who underwent either a trabeculectomy with MMC (n = 20) or AADI surgery (n = 21) with a minimum of 2 years follow-up. Outcome measures included intraocular pressure (IOP), the use of glaucoma medications, visual acuity, additional surgical interventions, and surgical complications. Surgical failure was defined as IOP > 21 mmHg or reduced < 20% from baseline, IOP ≤ 5 mmHg, reoperation for glaucoma or a complication, or loss of light perception vision. RESULTS: The cumulative probability of failure at 2 years was 50% in the trabeculectomy group (95%CI = 31-83%) and 24% in the AADI group (95%CI = 11-48%) (p = 0.09). The IOP was consistently lower in the AADI group compared with the trabeculectomy group at 6 months and thereafter. Surgical complications occurred in 13 eyes (65%) in the trabeculectomy group and 12 eyes (57%) in the AADI group (p = 0.71). Reoperations for glaucoma or complications were performed in 12 eyes (60%) in the trabeculectomy group and 5 patients (24%) in the tube group (p = 0.06). Cox proportional hazards showed that AADI had a 53% lower risk of failure at 2 years (p = 0.18; HR = 0.47; 95%CI = 0.16-1.40). CONCLUSION: AADI surgery achieved lower mean IOPs than trabeculectomy with MMC in managing glaucoma secondary to ICE syndrome. A trend toward lower rates of surgical failure and reoperations for glaucoma and complications was observed following AADI placement compared with trabeculectomy with MMC in eyes with ICE syndrome.

Mutant RAMP2 causes primary open-angle glaucoma via the CRLR-cAMP axis.

PURPOSE: Primary open-angle glaucoma (POAG) is the leading cause of irreversible blindness worldwide and mutations in known genes can only explain 5-6% of POAG. This study was conducted to identify novel POAG-causing genes and explore the pathogenesis of this disease. METHODS: Exome sequencing was performed in a Han Chinese cohort comprising 398 sporadic cases with POAG and 2010 controls, followed by replication studies by Sanger sequencing. A heterozygous Ramp2 knockout mouse model was generated for in vivo functional study. RESULTS: Using exome sequencing analysis and replication studies, we identified pathogenic variants in receptor activity-modifying protein 2 (RAMP2) within three genetically diverse populations (Han Chinese, German, and Indian). Six heterozygous RAMP2 pathogenic variants (Glu39Asp, Glu54Lys, Phe103Ser, Asn113Lysfs*10, Glu143Lys, and Ser171Arg) were identified among 16 of 4763 POAG patients, whereas no variants were detected in any exon of RAMP2 in 10,953 control individuals. Mutant RAMP2s aggregated in transfected cells and resulted in damage to the AM-RAMP2/CRLR-cAMP signaling pathway. Ablation of one Ramp2 allele led to cAMP reduction and retinal ganglion cell death in mice. CONCLUSION: This study demonstrated that disruption of RAMP2/CRLR-cAMP axis could cause POAG and identified a potential therapeutic intervention for POAG.

Surgical Outcomes of Early Versus Late Onset Glaucoma Associated With Sturge-Weber Syndrome.

PRCIS: Long-term intraocular pressure control can be difficult to achieve in eyes with Sturge-Weber syndrome glaucoma. The most commonly performed primary surgery was trabeculotomyin early onset disease and tube shunt implantation in late onset disease. PURPOSE: To compare long-term surgical outcomes of glaucoma associated with Sturge-Weber syndrome (SWS) in eyes with early and late-onset disease. METHODS: Medical records of children with glaucoma associated with SWS who underwent surgical treatment between January 1990 and December 2018 were reviewed. Those diagnosed ≤2 years of age were categorized as early onset while those who were diagnosed >2 years of age were late onset. Failure was defined as intraocular pressure (IOP) >21 mm Hg or reduced <20% below baseline on 2 consecutive follow-up visits after 3 months, IOP ≤5 mm Hg on 2 consecutive follow-up visits, reoperation for glaucoma or a complication, or loss of light perception. RESULTS: Forty-three eyes of 36 children were studied, including 26 eyes in the early-onset group and 17 eyes in the late-onset group. The early-onset group more frequently presented with buphthalmos, corneal edema, and Haab striae, while late-onset group had higher baseline IOP, larger cup-to-disc ratio, and longer axial length. The most commonly performed primary surgery was trabeculotomy (50%) in early-onset group and tube shunt implantation (71%) in late-onset group. The cumulative probability of failure after 5 years follow-up was 50.6% in early-onset group and 50.9% in the late-onset group ( P =0.56). Postoperative complications occurred in 3 eyes (12%) in early-onset group and 11 eyes (65%) in late-onset group ( P <0.001). CONCLUSIONS: Early and late-onset SWS glaucoma may represent 2 entities with different pathogenetic mechanisms, clinical presentations, primary surgical choices, and outcomes, though this needs corroboration in future studies.

Intermediate-term outcomes of the Aurolab aqueous drainage implant in neovascular glaucoma.

PURPOSE: To assess the outcomes of the non-valved Aurolab aqueous drainage implant (AADI) in neovascular glaucoma (NVG). METHODS: Data of consecutive patients with NVG who underwent AADI and had a minimum follow-up of 2 years were included. The primary outcome measure was the cumulative rate of surgical failure defined as intraocular pressure (IOP) >21 mm Hg or reduced <20% below baseline, IOP ≤5 mm Hg, reoperation for glaucoma or a complication, or loss of light perception vision. RESULTS: We included 85 eyes of 85 patients with NVG, with a mean age of 61.2±9.3 years. The most common aetiologies were proliferative diabetic retinopathy (n=43) and central retinal vein occlusion (n=24). The mean IOP decreased from 36.8±12.5 mm Hg at baseline to 15.8±7.5 mm Hg at 2-year follow-up (p<0.001) and the number of IOP-lowering medications reduced from 3.4±0.8 to 1.5±1.1 (p<0.001). The cumulative rate of failure increased from 3.1% (95% CI 1.1% to 11.8%) at 1 year to 33.8% (95% CI 20.4% to 52.5%) at 2 years. Multivariable analysis showed that eyes with open angles had a lower risk of failure (HR 0.17, 95% CI 0.10 to 1.03, p=0.09). The logarithm of minimum angle of resolution visual acuity declined from 0.98±0.7 to 1.8±1.0 at 2 years (p<0.001). CONCLUSION: Approximately one-third of NVG eyes that received the AADI failed after 2 years of follow-up similar to other series. Early AADI implantation at the open angle stage of NVG may yield better results.

Incidence, outcomes, and risk of surgical failure after development of early hypotony following Aurolab aqueous drainage implant surgery.

Purpose: To report the incidence, outcomes, and risk of surgical failure after early postoperative hypotony following Aurolab Aqueous Drainage Implant (AADI) surgery for adult and pediatric refractory glaucoma. Methods: Medical records of patients who underwent AADI between January 2013 and March 2017 with a minimum of 2-years follow-up were retrospectively reviewed. Early postoperative hypotony was defined as IOP ≤5 mmHg within the first 3 months after AADI. Surgical failure of AADI was defined as IOP >21 mmHg or reduced <20% below baseline on two consecutive follow-up visits after 3 months, IOP ≤5 mmHg on two consecutive follow-up visits after 3 months, reoperation for glaucoma or a complication, or loss of light perception vision. Results: Early postoperative hypotony was seen in 15/213 eyes (7%) in the adult group and in 6/101 eyes (6%) in the pediatric group. The onset of hypotony was significantly earlier in the pediatric group (median = 39 days post AADI, IQR = 20-58 days) compared with adult eyes (median = 51 days post AADI, IQR = 30-72 days) (P = 0.02). Eyes with early postoperative hypotony did not have an increased risk of cumulative surgical failure as compared with eyes without hypotony in both adult (33.3% vs. 23.7%; P = 0.48) and pediatric (33.3% vs. 13.7%; P = 0.16) refractory glaucoma. All eyes recovered from hypotony, though one adult eye developed retinal detachment and one pediatric eye developed corneal decompensation and lost vision. Conclusion: Early postoperative hypotony was an infrequent complication post AADI and occurred earlier in pediatric eyes. Early postoperative hypotony did not increase risk of surgical failure up to 2 years.

Long-term surgical outcomes of Aurolab aqueous drainage implant in pediatric eyes with primary congenital glaucoma versus aphakic glaucoma.

PURPOSE: To compare the outcomes of the Aurolab aqueous drainage implant (AADI) placed in eyes with refractory primary congenital glaucoma (PCG) versus aphakic glaucoma (APG). DESIGN: Retrospective comparative interventional case series. METHODS: Case files of consecutive eyes with PCG or APG that underwent AADI surgery between January 2013 and December 2016 and had a minimum 4 years follow-up were extracted from a computerised database. Failure was defined as intraocular pressure (IOP)>21 mm Hg or reduced<20% below baseline on two consecutive follow-up visits after 3 months, IOP≤5 mm Hg on two consecutive follow-up visits after 3 months, reoperation for glaucoma or a complication, or loss of light perception. RESULTS: Eighty-nine eyes underwent AADI placement, including 42 eyes (47%) with PCG and 47 eyes (53%) with APG. Both groups were comparable at baseline. At 1 year, the APG group had lower mean IOP (13.6±8.1 mm Hg vs 17.6±7.5 mm Hg, p=0.02) with use of fewer IOP-lowering medications (0.8±1.0 vs 1.5±1.0, p=0.01) than the PCG group. The cumulative failure rate at 4 years was 57% (95% CI 43% to 72%) in PCG versus 40% (95% CI 28% to 56%) in the APG eyes (p=0.11). Eyes with PCG had greater tube-related complications (48% vs 38%, p=0.07) and number of reoperations (40% vs 32%, p=0.02) compared with eyes with APG. CONCLUSIONS: Eyes with APG had relatively better outcomes after AADI placement compared with PCG during 4 years of follow-up. Reoperations accounted for more than 70% of the failures.

A Randomized Controlled Clinical Trial to Compare Conventional Drug Instillation to A Device Dropper Method in Medical Treatment of Glaucoma.

PURPOSE: To compare and analyze the performance of a device dropper (DD) over conventional drop instillation (CDI) method on ease of administration, compliance, patient satisfaction, and intraocular pressure (IOP) control in persons with glaucoma on ocular hypotensive medications. METHODS: We enrolled 72 individuals with primary open-angle glaucoma or ocular hypertension, on treatment with fixed combination (α agonist+ß blocker) drugs for at least 6 months. These were randomized into two groups (36 in each arm). Group 1 administered the drug with a DD and Group 2 used CDI method. Recruited individuals were interviewed for subjective difficulties using a formatted questionnaire at first month follow-up and IOP change from baseline was evaluated. RESULTS: Baseline demographic and ocular characteristics were similar in both groups. 57.1% in the conventional instillation and none in the DD had reported difficulty in using the eye drops on follow-up visit. DD group had significantly less spillage and contamination of eye surface or dropper tips, required minimal assistance, accurately targeted on first drop placement directly into the eye compared to CDI group (p-value<0.001). Mean IOP was comparable between the two groups. CONCLUSION: DD instillation method was observed to be easier to administer, more accurate in targeting the conjunctival cul-de-sac, reduced wastage with lesser contamination compared to the CDI technique. DDs may be expected to have better compliance and effectiveness in medical management of glaucoma.

Surgical Outcomes of Superotemporal Versus Inferonasal Placement of Aurolab Aqueous Drainage Implant in Refractory Pediatric Glaucoma.

PURPOSE: We sought to describe the outcomes of the Aurolab aqueous drainage implant (AADI) placed in the superotemporal (ST) versus the inferonasal (IN) quadrant in pediatric eyes with refractory glaucoma. DESIGN: Retrospective comparative interventional case series. METHODS: This was a retrospective study of patients ≤18 years of age who underwent AADI implantation and completed a minimum of 2-year follow-up. The choice of the quadrant depended upon the amount of scarring and conjunctival mobility. Cumulative success at 2 years was defined as intraocular pressure (IOP) ≤21 mm Hg or reduced by ≥20% below baseline on 2 consecutive follow-up visits after 3 months, IOP ≤5 mm Hg on 2 consecutive follow-up visits after 3 months, reoperation for glaucoma or a complication, or loss of light perception vision. RESULTS: A total of 144 patients (144 eyes) underwent AADI placement, including 48 eyes (33%) in the IN and 96 eyes (67%) in the ST quadrants. The IOP was significantly higher in the IN group (17.5 ± 7.4 mm Hg vs 13.7 ± 6.2 mm Hg, P = .005) with a greater number of medications (1.5 ± 1.0 vs 0.8 ± 0.9, P = .001) after 2 years of follow-up. Cumulative success rates at 2 years were 50.7% (95% confidence interval 35.4%-63.9%) in the IN group and 65.6% (95% confidence interval 56.5%-75.7%) in the ST group (P = .15). Complications occurred more frequently in the IN group, with significantly more tube exposure (12% vs 0%, P = .05). CONCLUSIONS: Placement of the AADI in the ST quadrant has better IOP-related outcomes and is a safer surgical option in pediatric eyes compared with the IN quadrant. It may be prudent to avoid AADI in the IN quadrant in children unless the ST location is not a viable option.

Incidence and Outcomes of Hypertensive Phase Following Aurolab Aqueous Drainage Implant Surgery in Adults with Refractory Glaucoma.

PURPOSE: To report the incidence and outcomes of hypertensive phase (HP) following Aurolab Aqueous Drainage Implant (AADI) (Aurolab) surgery in adults with refractory glaucoma. DESIGN: Retrospective, noncomparative, interventional case series. METHODS: All eyes that received the AADI and had a minimum of 2-year follow-up were identified, and data of patients who had intraocular pressure (IOP) ≤21 mm Hg at 6 weeks (ie, the time at which the tube-ligature suture dissolves) were used for statistical analysis. HP was defined as IOP >21 mm Hg during the first 3 months after the release of the tube ligating suture (with or without medications) in the absence of tube obstruction. RESULTS: A total of 200 eyes were included in the study, and HP was seen in 64 eyes (32%) with a peak IOP (mean ± SD) of 29.6 ± 7.8 mm Hg and peak incidence at 2-3 months after surgery. HP resolved within 3 months of its onset in 60 of the 64 eyes (94%) with additional IOP-lowering medications. The cumulative success rates were 71.8% (95% CI = 59.3%-81.2%) in HP eyes and 76.4% (95% CI = 68.7%-82.7%) in non-HP eyes (P = .23). Unadjusted Cox proportional hazards analysis showed that eyes experiencing HP had a marginally higher risk of failure (HR = 1.16, 95% CI = 0.6-2.1), but this relationship was not statistically significant (P = .61). CONCLUSIONS: A third of eyes that underwent AADI placement experienced HP. HP was successfully managed with additional IOP-lowering medications in a majority of cases and did not have a significant influence on long-term success rate.

Outcomes of Glaucoma Drainage Device Implantation and Trabeculectomy With Mitomycin C in Glaucoma Secondary to Aniridia.

PURPOSE: To compare the outcomes of Aurolab aqueous drainage implant (AADI; Aurolab) placement and trabeculectomy with mitomycin C (MMC) in patients with glaucoma secondary to aniridia. DESIGN: Retrospective comparative interventional case series. METHODS: This study included patients with congenital aniridia who underwent AADI implantation or trabeculectomy with MMC. Surgical failure was defined as IOP > 21 mm Hg or reduced <20% from baseline, IOP ≤ 5 mm Hg, reoperation for glaucoma or a complication, or loss of light perception vision. RESULTS: A total of 30 eyes of 30 patients underwent surgical treatment, including 18 eyes that received an AADI and 12 eyes that had a trabeculectomy with MMC. The cumulative probability of failure at 2 years was 11.1% (95% CI = 2.9%-37.6%) in the AADI group and 58.3% (95% CI = 33.5%-84.8%) in the trabeculectomy group (P = .05, log-rank). At 2 years, IOP (mean ± SD) was 14.1 ± 2.8 mm Hg in the AADI group and 19.6 ± 6.6 mm Hg in the trabeculectomy group (P = .02), and the number of glaucoma medications was 1.7 ± 0.9 in the AADI group and 2.2 ± 0.8 in the trabeculectomy group (P = .25). Surgical complications developed in 1 patient in each treatment group (P = .65). Cataract surgery was performed in 5 (42%) patients in the trabeculectomy group and no patients in the AADI group (P = .01). CONCLUSIONS: Placement of an AADI resulted in lower IOP and a higher rate of surgical success compared to trabeculectomy with MMC in eyes with glaucoma associated with aniridia. Cataract extraction was more frequently required after trabeculectomy with MMC than AADI implantation.

Aurolab Aqueous Drainage Implant With and Without Scleral Patch Graft in Refractory Adult and Pediatric Glaucomas: A Comparative Study.

PURPOSE: To compare the 2-year outcomes of eyes that received the Aurolab aqueous drainage implant (AADI) with and without a scleral patch graft. DESIGN: Retrospective comparative interventional case series. METHODS: Eyes with AADI and a minimum of a 2-year follow-up were included. Eyes that underwent implantation before January 2016 had surgery with a scleral patch graft covering the distal end of the tube, whereas those that were implanted after this period underwent surgery using a needle-generated scleral tunnel without the patch graft. The cumulative failure of the AADI was defined as intraocular pressure (IOP) >18 mm Hg or not reduced by 30% below baseline on 2 consecutive follow-up visits after 3 months. RESULTS: We included 215 adult eyes (n = 147 with patch graft, n = 68 without patch graft) and 111 pediatric eyes (n = 73 with patch graft, n = 38 without a patch graft). The mean IOP in eyes without the patch graft was higher at 1 month in adult eyes (before, 27.5 ± 14.1 vs after, 22.3 ± 11.1; P = .01) but not in pediatric eyes (14.3 ± before, 5.8 vs after, 17.8 ± 11.0; P = .39); there were no differences in IOP, vision, number of antiglaucoma medications, and complications between groups at all other time points. None of the eyes without the patch graft experienced tube exposure. Cumulative success rates at 2 years in adults (66.2% vs 63.9%, respectively; P = .85) were similar to those in children (77.2% vs 71.9%, respectively; P = .83) with both techniques. CONCLUSIONS: AADI placed without a scleral patch graft is as safe and effective as AADI placed with a patch graft in pediatric and adult refractory glaucomas.

In vitro and in vivo study on the secretion of the Gly367Arg mutant myocilin protein.

PURPOSE: Mutations in the myocilin gene (MYOC) leading to a perturbed outflow of aqueous in the trabecular meshwork (TM) has been associated with the pathophysiology of glaucoma. This study examines the expression of normal and mutant myocilin (Gly367Arg) in cultured TM cells. METHODS: Normal and mutant MYOC cDNA constructs were used to transfect the TM cells. In order to confirm the method of transfection, reverse transcriptase polymerase chain reaction (RT-PCR) was carried out. Further, confocal microscopic analysis was used to determine the cellular localization of myocilin protein. The extracellular nature of myocilin in the culture supernatant and cell lysates of the transfected cells was analyzed by western blot. Molecular modeling was done earlier using a knowledge based consensus method which involved threading the protein into the identified pentein fold for the COOH-terminal part. Molecular dynamics was carried out using GROMACS for the mutant model which was built using the native myocilin model. RESULTS: The Gly367Arg mutation causes accumulation of myocilin protein within TM cells with extensively reduced secretion contrary to wild type myocilin being characterized by intracellular localization and extracellular secretion. Further, Gly367Arg mutation occurs in a hydrophobic region which leads to burial of a charged residue. The dynamics suggests large conformational change is required to accommodate the mutation favoring aggregation of the protein. CONCLUSIONS: Our results suggest that Gly367Arg is a potential mutation that causes malfunction of TM cells either by dominant negative effect or gain of function of mutant myocilin. The structural model suggests that the mutated myocilin could aggregate, implying the possible role of Gly367Arg in causing Primary open angle glaucoma (POAG).

Identification and characterization of variants and a novel 4 bp deletion in the regulatory region of SIX6, a risk factor for primary open-angle glaucoma.

BACKGROUND: Primary open-angle glaucoma (POAG) is a complex disease of multigenic inheritance and the most common subtype of glaucoma. SIX6 encodes a transcription factor involved in retina, optic nerve, and pituitary development. Previous studies showed a genetic association between the SIX6 locus and POAG, identifying risk alleles. Whether these alleles are present also in the south Indian population is unclear. METHODS: To address this question, the SIX6 gene and an already characterized and highly conserved SIX6 enhancer (Ch14:60974427-60974430) were sequenced in two south Indian cohorts, respectively, composed of 65/65 and 200/200 POAG cases/age-matched controls. We next used Taqman-based allelic discrimination assay to genotype a common variant (rs33912345: c.421A>C) and the rs1048372 SNP in two cohorts, respectively, composed of 557/387 and 590/448 POAG cases/age-matched controls. An additional cohort of 153 POAG cases was subsequently recruited to assess the association of the rs33912345:c.421A>C and rs10483727 variants with more prominent changes in two POAG diagnostic parameters: retinal nerve fiber layer thickness and vertical cup/disc ratio, using spectral domain optical coherence tomography. The activity of the newly identified enhancer variants was assessed by transgenesis in zebrafish and luciferase assays. RESULTS: We identified two known rare and two common variants in the SIX6 locus and a novel 4 bp deletion in the analyzed enhancer. Contrary to previous studies, we could not establish a significant association between the rs10483727 and rs33912345:c.421A>C variants and PAOG in the south Indian ethnicity but patients carrying the corresponding C or T risk alleles exhibited a dose-dependent reduction of the thickness of the retinal nerve fiber layer and a significant increase in the vertical cup/disc ratio. Transgenesis in zebrafish and luciferase assays demonstrated that the newly identified 4 bp deletion significantly reduced reporter expression in cells of the retinal ganglion and amacrine layers, where human SIX6 is expressed. CONCLUSION: Altogether, our data further support the implication of SIX6 variants as POAG risk factors and implicates SIX6 haploinsufficiency in POAG pathogenesis.

Identification of novel mutant PAX6 alleles in Indian cases of familial aniridia.

BACKGROUND: Haploinsufficiency at the PAX6 locus causes aniridia, a panocular eye condition characterized by iris hypoplasia and a variety of other anterior and posterior eye defects leading to poor vision. This study was performed to identify novel PAX6 mutations that lead to familial aniridia in Indian patients. METHODS: Genomic DNA was isolated from affected individuals (clinically diagnosed aniridia) from nine unrelated aniridic pedigrees, unaffected family members, and unrelated normal controls. The coding regions of PAX6 were amplified and subjected to single strand conformation polymorphism (SSCP) gel analysis, and direct cloning and sequencing. RESULTS: SSCP band shifts, indicative of DNA base pair mutations, were observed in five of these unrelated families. Four mutations were shown to be previously unreported insertion or deletions in PAX6, leading to frameshifts. These new mutations were c.1174delTG (in exon 10), c.710delC (exon 6), c.406delTT (exon 5) and c.393insTCAGC (exon 5). The other nonsense mutation, a transition (c.1080C>T) in exon 9, has been reported previously as a mutation hotspot for PAX6 in other ethnic pedigrees. All mutant alleles transmitted through aniridic individuals in each family. CONCLUSION: These new deletions and an insertion create frameshifts, which are predicted to introduce premature termination codons into the PAX6 reading frame. The genetic alterations carried by affected individuals are predicted to lead to loss-of-function mutations that would segregate in an autosomal dominant manner to subsequent generations. This is the first report of the 'hotspot' c.1080C>T transition from Indian families.

PAX6 gene variations associated with aniridia in south India.

BACKGROUND: Mutations in the transcription factor gene PAX6 have been shown to be the cause of the aniridia phenotype. The purpose of this study was to analyze patients with aniridia to uncover PAX6 gene mutations in south Indian population. METHODS: Total genomic DNA was isolated from peripheral blood of twenty-eight members of six clinically diagnosed aniridia families and 60 normal healthy controls. The coding exons of the human PAX6 gene were amplified by PCR and allele specific variations were detected by single strand conformation polymorphism (SSCP) followed by automated sequencing. RESULTS: The sequencing results revealed novel PAX6 mutations in three patients with sporadic aniridia: c.715ins5, [c.1201delA; c.1239A>G] and c.901delA. Two previously reported nonsense mutations were also found: c.482C>A, c.830G>A. A neutral polymorphism was detected (IVS9-12C>T) at the boundary of intron 9 and exon 10. The two nonsense mutations found in the coding region of human PAX6 gene are reported for the first time in the south Indian population. CONCLUSION: The genetic analysis confirms that haploinsuffiency of the PAX6 gene causes the classic aniridia phenotype. Most of the point mutations detected in our study results in stop codons. Here we add three novel PAX6 gene mutations in south Indian population to the existing spectrum of mutations, which is not a well-studied ethnic group. Our study supports the hypothesis that a mutation in the PAX6 gene correlates with expression of aniridia.

Evaluation and understanding of myocilin mutations in Indian primary open angle glaucoma patients.

PURPOSE: To screen for mutations in the MYOC gene of patients with Primary Open Angle Glaucoma (POAG) in India and to better understand the mutations using a possible model of myocilin. METHODS: We analyzed DNA for mutations in 107 subjects with POAG and 90 normal control subjects. The exonic sequences of the MYOC gene from all subjects were amplified by Polymerase Chain Reaction (PCR). We carried out Single Strand Conformation Polymorphism (SSCP) for all the PCR products. The DNA samples which showed mobility shift in the banding pattern in SSCP gel were sequenced. We also analyzed the presence of the common mutation Gln368Stop using a specific restriction enzyme Taa 1. The mutations observed here and elsewhere have been mapped onto a possible model built for myocilin using a knowledge-based consensus modeling approach. RESULTS: Two heterozygous mutations Gly367Arg (1099G>A) and Thr377Met (1130C>T) were identified in exon3 of the MYOC gene of probands 40-1 and 51-1 respectively, from material obtained from the 107 unrelated subjects with POAG. These two mutations were not present in the normal controls studied. We identified a Single Nucleotide Polymorphism (SNP) Gly122Gly (366C>T) in exon1 of proband 57-1 as a non-disease causing variation. The common mutation Gln368Stop found in the Western population was not observed in the POAG cases screened in Indian population. The possible structural model for myocilin suggests a predominantly [beta]-strand rich C-terminal region (181-504) which is connected by the [alpha]-helical mid-region (111-180) to the N-terminal region (34-110) which has low secondary structure content. Both the mutations, Gly367Arg and Thr377Met identified in our study, map on to the C-terminal region. These mutations disfavor burial of this region during oligomer formation due to the charged or bulky nature of the mutants. Most of the other mutations known for myocilin also are surface exposed on the C-terminal region. CONCLUSIONS: Our findings indicate that the mutation frequency of the MYOC gene is 2% in the Indian population affected with POAG, which is not a well-studied ethnic group of the Asian continent. The variations identified in our study have been previously reported in the Western population. The nonsense mutation Gln368Stop was not observed in the present study and thereby suggests that it may not be a common disease-causing mutation in the Indian population. Amongst other Asian populations, studies in Japan also didn't report this nonsense mutation. The location of these mutations suggest that a plausible mode of action could be by disruption of dimer or oligomer formation by the C-terminal region allowing greater chances of nucleation of aggregation by the N-terminal region.

Lysyl oxidase-like 1 gene in the reversal of promoter risk allele in pseudoexfoliation syndrome.

IMPORTANCE: This study was necessary to establish the association between common genetic variants in the lysyl oxidase-like 1 (LOXL1) gene with pseudoexfoliation (PEX) syndrome and emphasize the reversal of promoter risk allele in a South Indian population. OBJECTIVE: To investigate the potential association of genetic variants across the LOXL1 gene in South Indian patients with PEX syndrome and glaucoma. DESIGN, SETTING, AND PARTICIPANTS: A case-control study of individuals from Madurai, India, with PEX syndrome and glaucoma as well as healthy people serving as controls. Three hundred unrelated people with PEX syndrome and 225 age- and ethnically matched controls were recruited for genetic analysis. MAIN OUTCOMES AND MEASURES: Four single-nucleotide polymorphisms in LOXL1 (rs16958477, rs1048661, rs3825942, and rs2165241) were genotyped by direct sequencing in all participants. Regulatory regions and 7 coding exons of LOXL1 were directly sequenced in 50 patients and 50 controls. A case-control association analysis was performed using the Golden Helix SVS suite. RESULTS: An association between 4 LOXL1 single-nucleotide polymorphisms with PEX syndrome and glaucoma was observed (rs16958477, P = 4.77 × 10-6 [odds ratio, 0.50]; rs1048661, P = 4.28 × 10-5 [1.79]; rs3825942, P = 4.68 × 10-30 [9.19]; and rs2165241, P = 1.98 × 10-15 [2.88]). Sequencing of 7 exons and regulatory regions of LOXL1 identified 11 additional sequence variants; only rs41435250 showed an association (P = 3.80 × 10-5 [0.49]) with PEX syndrome and glaucoma. CONCLUSIONS AND RELEVANCE: Genetic variants in LOXL1 are associated with PEX syndrome and glaucoma in the South Indian population. To our knowledge, this is the first study to demonstrate the association of rs41435250 with PEX as well as reversal of the promoter risk allele. Understanding the role of the LOXL1 gene in PEX pathogenesis will facilitate early detection in individuals at risk for this condition.

Genotype/phenotype association in Indian congenital aniridia.

The developmental birth eye disorder of iris is known as aniridia. Heterozygous PAX6 gene, which causes human aniridia and small eye in mice, is located on chromosome 11p13. The variability had been documented between the affected individuals within the families, is due to genotypic variation. Haploinsufficiency renders PAX6 allele non-functional or amorphic, however it presents hypomorphic or neomorphic alleles. India is not a well-studied ethnic group, hence the focus on congenital aniridia gene analysis supports the literature and the phenotypic association were analysed both in sporadic as well as familial. The consistent association of truncating PAX6 mutations with the phenotype is owing to non-sense-mediated decay (NMD). It is presumed that the genetic impact of increased homozygosity and heterozygocity in Indian counter part arises as the consequence of consanguineous marriages. The real fact involved in congenital aniridia with other related phenotypes with PAX6 mutations are still controversial.