Genetic association study of exfoliation syndrome identifies a protective rare variant at LOXL1 and five new susceptibility loci

Exfoliation syndrome (XFS) is the most common known risk factor for secondary glaucoma and a major cause of blindness worldwide. Variants in two genes, LOXL1 and CACNA1A, have previously been associated with XFS. To further elucidate the genetic basis of XFS, we collected a global sample of XFS cases to refine the association at LOXL1, which previously showed inconsistent results across populations, and to identify new variants associated with XFS. We identified a rare protective allele at LOXL1 (p.Phe407, odds ratio (OR) = 25, P = 2.9 × 10^-14) through deep resequencing of XFS cases and controls from nine countries. A genome-wide association study (GWAS) of XFS cases and controls from 24 countries followed by replication in 18 countries identified seven genome-wide significant loci (P < 5 × 10^-8). We identified association signals at 13q12 (POMP), 11q23.3 (TMEM136), 6p21 (AGPAT1), 3p24 (RBMS3) and 5q23 (near SEMA6A). These findings provide biological insights into the pathology of XFS and highlight a potential role for naturally occurring rare LOXL1 variants in disease biology.

The Cytokine Interleukin-6 and the Chemokines CCL20 and CXCL13 Are Novel Biomarkers of Specific Endogenous Uveitic Entities

PURPOSE

The purpose of this study was to determine levels of the cytokines IL-1β, IL-6, IL-21, IL-22, and IL-23 and the chemokines CXCL13, CCL19, CCL20, and CCL21 in aqueous humor (AH) samples from patients with specific uveitic entities.

METHODS

Paired serum samples (n = 13) and AH samples (n = 111) from patients with active idiopathic granulomatous uveitis (IGU) or with uveitis associated with HLA-B27-related inflammation, Behçet's disease (BD), Vogt-Koyanagi-Harada (VKH) disease, or sarcoidosis and control patients were analyzed in two different multiplex assays.

RESULTS

Cytokines IL-1β, IL-21, IL-22, and IL-23 were not detected in any AH sample. Chemokine CCL21 concentrations in serum were significantly higher than those in AH. CCL19 levels in AH and serum were not significantly different. Levels of CCL20 and CXCL13 in AH were significantly higher than those in serum. IL-6 was not detected in serum samples. IL-6 AH levels were significantly higher in patients with HLA-B27-associated uveitis and in BD patients than in patients with VKH disease, sarcoidosis, and IGU (P < 0.0001). CCL20 AH levels were significantly higher in HLA-B27-associated uveitis than in BD, VKH, sarcoidosis, and IGU (P = 0.001), whereas CXCL13 AH levels were significantly higher in VKH disease and IGU than in HLA-B27-associated uveitis, BD, and sarcoidosis (P = 0.007).

CONCLUSIONS

IL-6-driven immune responses are more potent in HLA-B27-associated uveitis and BD than in VKH disease, sarcoidosis, and IGU. CCL20 appears to be a specific biomarker of HLA-B27-associated uveitis, whereas CXCL13 appears to be a biomarker of VKH disease and IGU. Our findings suggest that IL-6, CCL20, and CXCL13 could serve as drug targets for treatment of specific clinical entities of endogenous uveitis.

Association of total antioxidants level with glaucoma type and severity

Objectives:

To compare the mean total antioxidant status (TAS) among 3 glaucoma types, namely: pseudoexfoliation glaucoma (PEG), primary open angle glaucoma (POAG), and primary angle closure glaucoma (PACG), and study its potential association with various clinical glaucoma-parameters.

Methods:

In this case-control study, plasma samples were obtained between September 2013 and October 2014 from 340 glaucoma patients (PEG [n=54]; POAG [n=147]; PACG [n=139]), and 351 controls of matching age, gender, ethnicity, and 5 different systemic co-morbidities from King Abdulaziz University Hospital, Riyadh, Saudi Arabia. The TAS in all samples was determined by a colorimetric-based assay.

Results:

The mean±standard deviation of TAS was significantly lower among cases: 0.77±0.32 than controls: 1.1±0.22, p<0.0001. Moreover, the TAS levels were significantly different across the 3 types of glaucoma: 0.86±0.24 in PEG, 0.47±0.32 in POAG, and 0.98±0.41 in PACG (all p<0.0001). In addition, there was a significant correlation between TAS and age at onset (Pearson correlation coefficient [R] 0.17, p<0.0001), cup/disc ratio (R: -0.13, p=0.004), and number of anti-glaucoma medications (R: -0.16, p=0.001).

Conclusion:

Our findings provide evidence that plasma TAS levels are decreased in patients with glaucoma, more so in POAG and PEG than PACG, supporting the hypothesis that decreased antioxidative defense and/or increased oxidative stress may have a critical role in the pathogenesis of glaucoma.

Polymorphism rs7555523 in transmembrane and coiled-coil domain 1 (TMCO1) is not a risk factor for primary open angle glaucoma in a Saudi cohort

Background

We investigated whether polymorphism rs7555523 (A > C) in human transmembrane and coiled-coil domain 1 (TMCO1) gene is a risk factor for primary open angle glaucoma (POAG) in a Saudi cohort.

Methods

A cohort of 87 unrelated POAG cases and 94 control subjects from Saudi Arabia were genotyped using Taq-Man® assay. The association of genotypes with POAG and other glaucoma specific clinical indices was investigated.

Results

The genotype and allele frequency of polymorphism rs7555523 at TMCO1 did not show any statistically significant association with POAG as compared to controls. The minor allele frequency was 0.103 in cases and 0.085 in controls. Except for awareness of glaucoma (p = 0.036), no significant association of genotypes were seen with glaucoma specific clinical indices such as intraocular pressure (IOP), cup/disc ratio and number of anti-glaucoma medications used. Binary logistic regression analysis (adjusted for age and gender) showed that age was a significant indicator for the development of glaucoma in this group (adjusted odds ratio = 1.2; 95 % confidence interval = 1.078–1.157; p < 0.001).

Conclusion

Our study was unable to replicate the findings of previously reported association for polymorphism rs7555523 in TMCO1 with POAG and related clinical indices such as IOP and cup/disc ratio indicating that this variant is not a risk factor for POAG in the Saudi cohort.

Analysis of Polymorphism rs1900004 in Atonal bHLH Transcription Factor 7 in Saudi Patients with Primary Open Angle Glaucoma

AIMS

To investigate the association between the rs1900004 polymorphism in the atonal bHLH transcription factor 7 (ATOH7) gene and primary open angle glaucoma (POAG) in Saudi patients.

METHODS

Eighty-seven unrelated POAG cases and 94 unrelated control subjects of Saudi origin were genotyped utilizing a TaqMan^® assay. The association between mutant genotypes and POAG and its related clinical indices was investigated.

RESULTS

The genotype and allele frequencies of the polymorphism in ATOH7 did not show any statistically significant association with POAG compared to controls. The minor allele frequency was 0.32 in both cases and controls. None of the demographic, systemic diseases nor glaucoma-specific clinical indices such as intraocular pressure (IOP), cup/disc ratio, and number of antiglaucoma medication, showed any significant association with genotypes. Binary logistic regression analysis (adjusted for age and gender) showed that age was a marginally significant risk factor for the development of glaucoma (adjusted odds ratio = 1.1; 95% confidence interval = 1.079-1.158; p < 0.0001).

CONCLUSIONS

The study did not detect any direct link between genotype/allele frequency of rs1900004 in ATOH7 and POAG or its related clinical indices such as IOP and cup/disc ratio indicating that this polymorphism is not a risk factor for POAG in a Saudi cohort.

Analysis of Cyclin-Dependent Kinase Inhibitor-2B rs1063192 Polymorphism in Saudi Patients with Primary Open-Angle Glaucoma

AIMS

To investigate whether the polymorphism rs1063192 (A>G) in the cyclin-dependent kinase Inhibitor-2B (CDKN2B) gene is a risk factor for primary open-angle glaucoma (POAG).

METHOD

A case-control study was conducted wherein we genotyped 87 unrelated POAG cases and 94 control subjects from Saudi Arabia using the Taq-Man^® assay.

RESULTS

The minor allele frequency was 0.20 in POAG cases and 0.21 in controls. Both the genotype and allele frequencies were not significantly different between cases and controls. No significant association was found between genotypes and glaucoma clinical indices, except that the mutant homozygous genotype (G/G) was associated with the family history of glaucoma (p = 0.024).

CONCLUSION

Polymorphism rs1063192 in CDKN2B is not a risk factor for POAG in Saudi cohort.

Lack of Association Between Polymorphism rs4986791 in TLR4 and Primary Open-Angle Glaucoma in a Saudi Cohort

AIMS

To investigate whether single nucleotide polymorphism (SNP) rs4986791 (C>T) in the toll-like receptor 4 (TLR4) gene is a risk factor for primary open-angle glaucoma (POAG) in the Saudi population.

METHOD

A case-control study was performed to genotype a cohort of 85 POAG patients and 95 matched healthy controls utilizing TaqMan(®). The association between mutant genotypes and various POAG clinical indices were investigated.

RESULTS

The wild-type (C/C), heterozygous (C/T), and homozygous (T/T) genotypes were observed in 85.9%, 12.9%, and 1.2% POAG cases, respectively, compared to 91.6%, 8.4%, and none, respectively, among controls. The minor allele frequency was 0.076 in cases and 0.042 in controls. Both the genotype and allele frequency among POAG cases and controls did not vary significantly. With the exception of family history of glaucoma (p = 0.032), no significant association of genotypes was seen with age, intraocular pressure, cup/disc ratio, number of antiglaucoma medications, and other systemic comorbidities among the POAG cases.

CONCLUSION

We did not detect any direct association between genotypes or allele frequencies of SNP rs4986791 in the TLR4 gene and POAG.

Analysis of toll-like receptor rs4986790 polymorphism in Saudi patients with primary open angle glaucoma

BACKGROUND

To investigate whether SNP rs4986790 in toll-like receptors (TLRs) is a risk factor for primary open angle glaucoma (POAG) in a Saudi population.

MATERIALS AND METHODS

A cohort of 85 unrelated POAG patients and 95 unrelated control subjects from Saudi Arabia were genotyped utilizing Taq-Man® assay. The association between mutant genotypes and various clinical indices important for POAG was investigated.

RESULTS

Among cases, the normal pattern (A/A) was detected in 70 (82.4%) of the subjects, A/G in 14 (16.5%) and G/G in one subject only (1.2%). Among controls, prevalence of the genotype (A/A) was detected in 86 (90.5%), the (A/G) genotype in 8 (8.4%) and homozygous mutated genotype (G/G) in 1 (1.1%) subjects. Comparing cases to controls, the odds ratio of having heterozygous mutation (A/G) was 2.15 [95% CI: 0.853-5.417], which was not significant (p = 0.114). The odds ratio of having homozygous mutation (G/G) was 1.22 [95% CI: 0.075-19.99], which was statistically non-significant (p = 0.568). Likewise, the presence of the mutated allele (G) was non-significantly different between cases and controls (p = 0.154). Comparing cases to controls as regards co-morbidity with other systemic diseases, there were no statistically significant differences between groups in all assessed diseases except for a family history of glaucoma (p = 0.014) Conclusions: In conclusion, we could not detect any direct link between genotypes or allele frequencies of SNP rs4986790 in the TLR4 gene and POAG. In contrast, genotype (A/A) may be protective against POAG especially among individuals with no family history of glaucoma.

Analysis of Toll-Like Receptor 2 Polymorphism (rs5743704) in Saudi Patients with Primary Open-Angle Glaucoma

AIMS

To investigate whether the single-nucleotide polymorphism (SNP) rs5743704 in the toll-like receptor 2 gene is associated with primary open-angle glaucoma (POAG) or any of its clinical indices in a Saudi cohort.

METHOD

Ninety-five unrelated POAG cases and 95 controls of Saudi origin were genotyped utilizing a TaqMan(®) assay. The association between genotypes and various clinical indices important for POAG were investigated.

RESULTS

The genotypic and allelic frequencies among cases were not significantly different when compared to controls. The minor allele frequency was 0.021 in cases and 0.011 in controls. No significant association was seen with intraocular pressure and cup/disc ratio. However, carriers of the C/A genotype had higher number of anti-glaucoma medications compared to controls (p = 0.04).

CONCLUSION

SNP rs5773704 is not associated with POAG in a Saudi population. Despite sample size limitation, the association of the minor allele A with higher number of anti-glaucoma medications suggests a possible indirect role for this SNP in predicting disease severity.

A common variant near TGFBR3 is associated with primary open angle glaucoma

Primary open angle glaucoma (POAG), a major cause of blindness worldwide, is a complex disease with a significant genetic contribution. We performed Exome Array (Illumina) analysis on 3504 POAG cases and 9746 controls with replication of the most significant findings in 9173 POAG cases and 26 780 controls across 18 collections of Asian, African and European descent. Apart from confirming strong evidence of association at CDKN2B-AS1 (rs2157719 [G], odds ratio [OR] = 0.71, P = 2.81 × 10⁻³³), we observed one SNP showing significant association to POAG (CDC7–TGFBR3 rs1192415, OR_G-allele = 1.13, P_meta = 1.60 × 10⁻⁸). This particular SNP has previously been shown to be strongly associated with optic disc area and vertical cup-to-disc ratio, which are regarded as glaucoma-related quantitative traits. Our study now extends this by directly implicating it in POAG disease pathogenesis.

A common variant mapping to CACNA1A is associated with susceptibility to exfoliation syndrome

Exfoliation syndrome (XFS) is the most common recognizable cause of open-angle glaucoma worldwide. To better understand the etiology of XFS, we conducted a genome-wide association study (GWAS) of 1,484 cases and 1,188 controls from Japan and followed up the most significant findings in a further 6,901 cases and 20,727 controls from 17 countries across 6 continents. We discovered a genome-wide significant association between a new locus (CACNA1A rs4926244) and increased susceptibility to XFS (odds ratio (OR) = 1.16, P = 3.36 × 10(-11)). Although we also confirmed overwhelming association at the LOXL1 locus, the key SNP marker (LOXL1 rs4886776) demonstrated allelic reversal depending on the ancestry group (Japanese: OR(A allele) = 9.87, P = 2.13 × 10(-217); non-Japanese: OR(A allele) = 0.49, P = 2.35 × 10(-31)). Our findings represent the first genetic locus outside of LOXL1 surpassing genome-wide significance for XFS and provide insight into the biology and pathogenesis of the disease.

Total antioxidant level is correlated with intra-ocular pressure in patients with primary angle closure glaucoma

Background

To evaluate total antioxidant status (TAS) in the plasma of primary angle closure glaucoma (PACG) patients and to compare it to that of the control group. Additionally, we aim to investigate the association of various PACG clinical indices with TAS level.

Methods

Plasma samples were obtained from 139 PACG patients and 149 glaucoma-free controls of matching age, sex, and ethnicity. TAS in all samples was determined by spectrophotometric and enzyme-linked immunosorbent assay methods. We studied the possible association of the TAS level with various clinical indices relevant to PACG.

Results

The mean (±SD) total antioxidant (TAS) value was almost similar in patients 1 (±0.22) compared to controls 0.97 (±0.43); p = 0.345. Among cases, mean TAS concentration showed a statistically significant lower pattern among subjects with glaucoma onset at the age of ≤ 50 years (p = 0.037) and female subjects (p = 0.014) as well as having a family history of glaucoma (p = 0.010). Interestingly, a statistically significant inverse correlation was detected between TAS concentration and intra ocular pressure (IOP), (R = -0.14, p = 0.037).

Conclusions

The inverse correlation of TAS level with IOP, highlights TAS potential role as a predictive-marker for PACG-severity.

Decreased total antioxidants in patients with primary open angle glaucoma

PURPOSE

To evaluate total antioxidant status (TAS) in the plasma of primary open angle glaucoma (POAG) patients and to compare it to that of the control group. Additionally, we aim to investigate the association of various POAG clinical indices with TAS level.

MATERIALS AND METHODS

Plasma samples were obtained from 139 POAG patients and 148 glaucoma-free controls of matching age, sex, and ethnicity. TAS in all samples was determined by spectrophotometric and enzyme-linked immunosorbent assay methods.We studied the possible association of the TAS level with various clinical indices relevant to POAG.

RESULTS

The mean (±SD) total antioxidant (TAS) value was lower among patients: 0.47 (±0.32), than controls: 0.97 (±0.43) and this difference was statistically significant (p<0.0001). TAS concentration was not significantly associated neither with the level of intraocular pressure, nor with number of anti-glaucoma medications (p = 0.532 and 0.084 respectively). However, TAS level shows a trend towards reduction with increased severity of glaucoma presented in a reversed significant association with cup/disc ratio (p = 0.043).

CONCLUSIONS

Our findings provide evidence that TAS decreases in the plasma of POAG patients and that it may play a role in POAG pathogenesis. Association of TAS level with increased cup-to-disc ratio highlights TAS potential role as a predictive-marker for POAG-severity.

Association of SOD2 Mutation (c.47T > C) with Various Primary Angle Closure Glaucoma Clinical Indices

We investigated whether the c.47T>C polymorphism (SNP rs4880) in the manganese superoxide dismutase (SOD2) gene is a risk factor for primary angle closure glaucoma (PACG) in the Saudi population. Among cases (n=139), the prevalence of various genotypes were 25.9%, 46.8% and 27.3% for T/T, C/T and C/C genotypes respectively. This trend was similar in the controls (n=403); 22.6%, 50.1% and 27.3% for T/T, C/T and C/C respectively. The differences in genotype distribution were not statistically significant (p=0.391 and 0.682 respectively). The minor allele frequency was 50.7% in cases and 52.4% in controls; this difference was not statistically significant (p=0.676). Investigating the potential association between this SOD2 polymorphism and different clinical indices, there was a statistically significant difference among different genotype groups in terms of three important clinical indices for PACG; Mean age at onset, duration of onset to and the mean LogMAR visual acuity (p=0.041, 0.018 and 0.033 respectively). The three markers are highly associated prognostic factors to diseases severity. If our results are proven in larger cohort and in various populations, then this SNP may have potentiality to be used as an indicator for PACG severity.

A catalase promoter variant rs1001179 is associated with visual acuity but not with primary angle closure glaucoma in Saudi patients

Background

To Investigate whether the g.4760C>T polymorphism in the promoter region of the catalase gene (CAT) is a risk factor for primary angle closure glaucoma (PACG) in the Saudi population.

Methods

138 unrelated PACG patients and 403 unrelated control subjects from Saudi Arabia were genotyped for a single nucleotide polymorphism (SNP; rs1001179; g.4760C>T) utilizing Taq-Man® assay. The association between different genotypes and various clinical indices important for PACG was also investigated.

Results

The distribution of different genotypes was comparable between both study groups. The genotype “C/C” was predominant among cafses; 94 (68.1%) and controls; 289 (71.7%). Heterozygous genotype “C/T”, was present in 41 (29.7%) of cases and 103 (25.6%) of controls, where the homozygous variant genotype was present in only 3 (2.2%) of cases and 11 (2.7%) of the controls. The distribution of variant allele was similar in both study groups (p= 0.568). Interestingly, there was a trend of association between the type of the variant (homozygous variant, heterozygous and wildtype genotype) and one important parameter for PACG, which is visual acuity. The visual acuity increase was; 0.62 (±0.74), 0.88 (±0.88) and 1.27 (±0.95) in patients carrying the “C/C”, “C/T” and “T/T” genotypes respectively, which was statistically significant in both ANOVA and pairwise individual T tests (p = 0.022, 0.031 and 0.039) when compared to controls.

Conclusions

This variant is possibly associated with visual acuity in PACG patients and thus had the potential to be used as a parameter for assessing PACG severity.

Analysis of catalase SNP rs1001179 in Saudi patients with primary open angle glaucoma

PURPOSE

To investigate whether the g.4760C > T mutation in the catalase gene (CAT) is a risk factor for primary open angle glaucoma (POAG) in the Saudi population.

METHODS

A cohort of 225 unrelated POAG patients and 403 unrelated control subjects from Saudi Arabia were genotyped for a single nucleotide polymorphism (SNP; rs1001179; g.4760C > T) in the CAT gene utilizing Taq-Man® assay. The association between mutant genotypes and various clinical indices important for POAG was also investigated.

RESULTS

The distribution of different genotypes was comparable between both study groups. The genotype "C/C" was predominant among cases; 169 (75.1%) as well as among the controls; 289 (71.7%). As for the heterozygous mutated genotype "C/T", it was present in 52 (23.1%) of cases and 103 (25.6%) of controls, where the homozygous fully mutated genotype was present in only 4 (1.8%) of cases and 11 (2.7%) of the controls. The distribution of mutant allele was similar in both study groups (p = 0.218). Interestingly, there was a trend of association between the type of the mutation (homozygous versus heterozygous) and three clinical parameters important for predicting the severity of the disease. These parameters include mean age of onset, mean level of intraocular pressure (IOP) and mean months of duration of encountering glaucoma.

CONCLUSIONS

There were no statistically significant differences between cases and controls in terms of the different genotype distribution. This mutation is possibly associated with various clinical indices important for POAG and thus may be used as a parameter for assessing POAG severity, at least in this population.

Efficacy and safety of non-penetrating deep sclerectomy surgery in Saudi patients with uncontrolled open angle glaucoma

OBJECTIVE

To investigate the efficacy and safety of deep sclerectomy (DS) in Saudi patients with primary and secondary open-angle glaucoma (OAG).

METHODS

In this retrospective cohort study, a total of 194 eyes of 152 patients with OAG were consecutively enrolled to undergo DS with Mitomycin-C (MMC) at King Abdulaziz University Hospital, Jeddah, Kingdom of Saudi Arabia between January 2002 and September 2010. Age at surgery, gender, type of glaucoma, operated eye, previous ocular surgery, type of implant, pre and final visit visual acuities, intraocular pressure (IOP), number of anti-glaucoma medications, optic nerve cup/disc ratio, and complications were recorded.

RESULTS

Cases were followed up to a mean of 60.9 (+/-49.7) months. The IOP reduced from a preoperative mean of 25.6 (+/-10.3) to final visit of 13.5 (+/-4), whereas the mean number of anti-glaucoma medication also reduced from 2.95 (+/-0.93) to 0.22 (+/-0.63), which was statistically significant (p<0.0001). Complete success was 82%, while overall success was 90.2%. Patients <50 years (p=0.003), high IOP (>/=21) at baseline (p=0.039), and being exposed to previous surgeries (p=0.047) were significant risk factors for failure, while combining cataract and converting to penetrating surgery have significantly improved the success rate (p=0.037).

CONCLUSION

Deep sclerectomy provides significant IOP reduction with low rate of visual threatening complications in Saudi patients with open angle glaucoma.

Lack of association of SNP rs4236601 near CAV1 and CAV2 with POAG in a Saudi cohort

PURPOSE

To determine the role of the recently discovered primary open angle glaucoma (POAG) single nucleotide polymorphism (SNP) rs4236601 near the caveolin-1 (CAV1) and CAV2 among patients and controls from Saudi Arabia.

METHODS

A cohort of 220 POAG patients and 405 control subjects from Saudi Arabia were genotyped for a SNP (rs4236601;g.2891 G>A) in the chromosome 7q31 locus near CAV1 and CAV2 using a standard polymerase chain reaction (PCR) and sequencing method.

RESULTS

The minor allele frequency (MAF) of rs4236601 was 0.3 in controls and 0.31 in POAG patients. We detected no statistical difference when we compared the allele frequencies between POAG patients and control subjects (p=0.699). Similarly, we detected no statistical difference in the frequency of the three possible rs4236601 genotypes between patients and controls. The p-values were 0.928 and 0.683 for heterozygous genotype (G/A) and homozygous mutant genotype (A/A), respectively. We found no statistically significant difference among patients with any of the three possible genotypes and various clinical indices important for glaucoma. Among patients with homozygous (A/A), the mean IOP was higher (21.4) compared to patients with G/G wildtype (20.4) and to patients with G/A genotype (18.5). However, this apparent difference did not reach the statistical significance threshold (p=0.062).

CONCLUSIONS

We were unable to detect this association in our POAG-patients from Saudi Arabia, suggesting that this risk factor may not have a strong effect in all populations. A founder effect may play a role in certain populations where the link was established.

Screening of CYP1B1 and LTBP2 genes in Saudi families with primary congenital glaucoma: genotype-phenotype correlation

PURPOSE

Primary congenital glaucoma (PCG) is a severe form of glaucoma that presents early in life. PCG is a clinical and genetic entity that is distinct from juvenile forms of glaucoma. Inheritance is usually autosomal recessive and therefore the disease might be more common in societies where consanguinity is high. We studied the prevalence of cytochrome P450, family 1, subfamily B, polypeptide 1 (CYP1B1) and latent-transforming growth factor beta-binding protein 2 (LTBP2) mutations in a group of Saudi PCG patients and attempted to correlate the mutation status with the disease severity.

METHODS

Genomic DNA was collected from 54 unrelated Saudi PCG families (74 patients) who were diagnosed as having PCG by standard ophthalmological examinations and screened for mutations in CYP1B1 and LTBP2 by sequencing. We also examined the effect of mutations on the phenotype of patients with PCG (phenotype-genotype correlation).

RESULTS

Mutations in CYP1B1 were identified in 41 (75.9%) of affected patients. No mutation in CYP1B1 was found in 13 (24.1%) affected persons. We detected a total of 13 mutations: 9 missense mutations (G61E, A119S, R390H, P437L, D441G, A443G, G466S, G466D, and R469W), 2 deletions (g.4238_4247del and g.7901_7913del), and 2 nonsense mutations (R355X and R444X). Two mutations, G466S and D441G, were novel. The G61E mutation was by far the most common mutation detected. PCG cases with CYP1B1 mutation(s) presented with a high degree of haze and greater cup/disc ratio than those with no mutation(s). Also, PCG cases with a mutation had higher post operative indices in terms of post operative haze and the need for anti-glaucoma medications. Additionally, the surgical success rate was higher 13/14 (92.9%) among cases without mutation than those with mutation 42/60 (70%). No mutation(s) were found in LTBP2 in any of the tested patients.

CONCLUSIONS

CYP1B1 mutations are the predominant cause of PCG in the Saudi Arabian population with G61E as the dominant disease-associated allele. PCG cases with a mutation had higher last postoperative visit indices in terms of postoperative haze and the need for anti-glaucoma medications. This will be a valuable parameter in predicting disease severity earlier on and might help in predicting the surgical outcome.

Decreased total antioxidants status in the plasma of patients with pseudoexfoliation glaucoma

PURPOSE

To evaluate total antioxidant status (TAS) in the plasma of pseudoexfoliation glaucoma (PEG) patients and to compare this level with a matching control group. Additionally, we aim to investigate the effect of the combined action of the lysyl oxidase-like 1 (LOXL1) mutation status with TAS level on the development of PEG.

METHODS

Plasma samples were obtained from 54 PEG patients and 54 controls of matching age, sex, and ethnicity. TAS in all samples was determined by spectrophotometric and enzyme-linked immunosorbent assay methods. The coding region of LOXL1, where it encompasses both single nucleotide polymorphisms (SNPs; rs1048661 and rs3825942), was sequenced.

RESULTS

The mean (±SD) total antioxidant (TAS) value was lower among patients: 0.87 (0.24), range 0.9-1.41 than controls: 1.07 (0.23), range 0.72-1.94, and this difference was statistically significant (p<0.0001: 95%CI: -0.295-0.114). Evaluating the impact of age, sex, and the mutation in addition to the mean TAS value in patients with PEG, a logistic regression analysis was conducted using diseased/not diseased as the outcome of interest (the dependent variable). Results show that, controlling for all other variables, mean TAS value (p<0.0001) and the mutation G/G in rs3825942 (p=0.041) are significant risk factors for PEG.

CONCLUSIONS

Our findings provide evidence that TAS decreases in the plasma of PEG patients, suggesting that TAS may have an important role in the pathogenesis of PEG. The combined effect of the "G" allele and the decreased TAS may contribute to the overall pathogenesis of PEG.

Susceptibility to primary angle closure glaucoma in Saudi Arabia: the possible role of mitochondrial DNA ancestry informative haplogroups

PURPOSE

In a previous preliminary analysis we reported that mitochondrial DNA (mtDNA) haplogroup R0a was significantly more frequent in primary angle closure glaucoma (PACG) Saudi patients than in healthy Saudi controls. This result prompted us to extend our work using a significant larger Saudi PACG cohort and more healthy controls.

METHODS

We sequenced the mtDNA regulatory hypervariable region-I (HVS-I) and coding regions, comprising haplogroup diagnostic polymorphisms, in 227 PACG Saudi patients and compared their haplogroup frequencies with those obtained from 186 matched healthy controls (free of PACG by examination) and from a large sample of 810 healthy Saudi Arabs representing the general Saudi population.

RESULTS

MtDNA Haplogroups R0a and J, the most abundant lineages in Saudi Arabia, were in significant higher frequencies in the PACG patients than in controls, while the widespread western Eurasian haplogroup U was associated with reduced risk to developing PACG.

CONCLUSIONS

Haplogroups R0a and J could be ancestry informative markers for PACG in the Saudi Arabian population. In addition, the western Eurasian haplogroup U may play a mild protective effect to this illness.

Mitochondrial DNA lineages of African origin confer susceptibility to primary open-angle glaucoma in Saudi patients

PURPOSE

We previously reported that certain mitochondrial DNA (mtDNA) polymorphisms in the coding region may be involved in the pathogenesis for primary open-angle-glaucoma (POAG). This encouraged us to extend our work and assess whether mtDNA diagnostic polymorphisms, defining geographically structured haplogroups, could be associated with the development of POAG.

METHODS

We sequenced the mtDNA regulatory hypervariable region-I (HVS-I) region and coding regions, comprising haplogroup diagnostic polymorphisms, in 176 POAG patients and 186 matched healthy controls (free of glaucoma by examination) of Saudi Arabia ascendancy. A large sample of 810 healthy Saudi Arabs representing the general Saudi population has also been included in the analysis. Assigning individuals into various mitochondrial haplogroups was performed using the nomenclature previously described for African and for Eurasian sequences.

RESULTS

African mtDNA haplotypes belonging to L haplogroups, excluding L2, confer susceptibility to POAG whereas the Eurasian haplogroup N1 was associated with reduced risk of developing POAG in Saudi Arabian population.

CONCLUSIONS

Saudi individuals with mtDNA of African origin are at higher risk of developing POAG. In addition, the mtDNA Eurasian haplogroup N1 may play a mild protective effect to this illness.