Tahira Sultan

Analysis of the SOD1 Gene in Keratoconus Patients from Saudi Arabia

Abstract We investigated Saudi patients with familial and sporadic Keratoconus for mutations in the Superoxide dismutase 1, soluble (SOD1) gene. We sequenced the entire coding region, exon-intron boundaries and intron 2 encompassing a 7-bp deletion in clinically confirmed Keratoconus patients (n = 55) and 100 ethnically matched healthy controls. All cases and controls were unrelated. Sequencing the SOD1 gene revealed the presence of four nucleotide changes and all were non-coding. Those were g.12035 C > A; g.13978 T > A; g.12037 G > A and g.11931 A > C with similar frequencies in patients and controls. All four sequence changes were benign polymorphisms with no apparent clinical significance. Additionally, the 7-bp deletion in intro2 reported previously, were not detected in any of our Keratocnus cohort. In our Keratoconus cohort, no pathogenic SOD1 mutation(s) was identified.

Mitochondrial sequence changes in keratoconus patients.

PURPOSE We investigated whether a group of patients with keratoconus (KTCN) harbor mutations in the mitochondrial genome. METHODS We sequenced the full mitochondrial genome in a group of Saudi patients with KTCN (n = 26) and 100 ethnically matched controls who had no KTCN by examination. RESULTS A total of 10 KTCN patients (38.5%) had potentially pathogenic nonsynonymous mtDNA mutations. Of the nonsynonymous sequence changes detected, 4 (40%) were in Complex I, one was in the tRNA(Glutamine), one was in tRNA(Tryptophan), one was in tRNA(Asparagine), one was in tRNA(Histidine), and two were in the tRNA(Leucine2). One nonsynonymous sequence change was heteroplasmic, whereas all the remaining 9 were homoplasmic. These sequence changes were not detected in controls of similar ethnicity. Four sequence changes were novel (were not reported previously) and 5 were reported previously. Additionally, we detected 54 synonymous (does not result in an amino acid change) sequence changes with no pathologic significance. CONCLUSIONS If our results are confirmed in a larger cohort and multiple ethnicities, then mtDNA mutation may be considered as a genetic risk factor contributing indirectly through the oxidative stress mechanism to the development and/or progression of KTCN.

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.

Association of mitochondrial haplogroups H and R with keratoconus in Saudi Arabian patients.

PURPOSE Keratoconic corneas exhibit more mitochondrial DNA (mtDNA) damage than do normal corneas and thus mtDNA may represent a potential candidate for genetic susceptibility studies in keratoconus. To test this hypothesis we determined mitochondrial haplogroups in Saudi patients with keratoconus and healthy controls of same ethnicity. METHODS Mitochondrial haplogrouping was performed by polymerase chain reaction-based automated Sanger sequencing in 114 patients with keratoconus and 552 healthy controls. RESULTS Mitochondrial haplogroups H and R were significantly overrepresented in patients with keratoconus (28.9% vs. 8.5%, P < 0.0001 and 17.5% vs. 3.1%, P < 0.0001, respectively) as compared to healthy controls. CONCLUSIONS Our data suggest that individuals with mitochondrial haplogroups H and R are at increased risk to develop keratoconus. In addition, the results provide further evidence for a plausible role of mtDNA in keratoconus etiology.

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

BackgroundTo 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.MethodsPlasma 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.ResultsThe 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).ConclusionsThe inverse correlation of TAS level with IOP, highlights TAS potential role as a predictive-marker for PACG-severity.

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

BackgroundTo 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.Methods138 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.ResultsThe 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.ConclusionsThis 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 toll-like receptor rs4986790 polymorphism in Saudi patients with primary open angle glaucoma

ABSTRACT 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.

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

Abstract 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.

Association of increased levels of plasma tumor necrosis factor alpha with primary open-angle glaucoma

Purpose Retinal ganglion cell (RGC) death is a key feature of glaucoma. Elevated levels of tumor necrosis factor alpha (TNF-α), a pro-inflammatory cytokine, can induce RGC apoptosis and play a critical role in glaucomatous neurodegeneration. Based on the possible role of inflammation and oxidative stress in the pathogenesis of primary open-angle glaucoma (POAG), we investigated the association between plasma levels of TNF-α and POAG or its clinical indices in comparison to non-glaucomatous controls. Patients and methods In a case–control retrospective cohort of 51 POAG cases and 88 controls, plasma TNF-α levels were measured using an enzyme-linked immunosorbent assay (ELISA). The assay was performed in duplicates on an automated ELISA analyzer. Results Mean TNF-α level was significantly elevated in POAG cases (1.88 ± 2.17 pg/mL) than the controls (0.93 ± 1.49 pg/mL; p = 0.003). The overall dose–response trend was significant (χ2 = 6.12, df = 2; p = 0.047). No statistical difference was seen in age, gender and systemic disease distribution. A modest negative and significant correlation was seen between TNF-α level and number of antiglaucoma medications, an important clinical index of POAG severity. Moreover, logistic regression analysis showed that the risk of POAG was most significantly affected by TNF-α level and not by age and sex. Conclusion High systemic level of an inflammatory cytokine, TNF-α, is associated with POAG; however, its possible use as a biomarker for early glaucoma diagnosis and/or disease severity needs further investigation.

Analysis of CYP1B1 sequence alterations in patients with primary open-angle glaucoma of Saudi origin

Cytochrome P450 Family 1 Subfamily B Member 1 (CYP1B1; OMIM# 601771) gene encodes one of the cytochrome P450 family of enzymes. CYP1B1 mutations have been associated primarily with primary congenital glaucoma (PCG). Similar studies were reported in juvenile open-angle glaucoma, Rieger’s and Peters anomalies. Reports of likely pathogenic sequence alterations in families affected with adult-onset primary open-angle glaucoma (POAG) triggered this investigation. We screened unrelated POAG cases and healthy controls for mutations in CYP1B1 using automated Sanger sequencing to identify five known polymorphisms and one CYP1B1 mutation (p.G61E) in a heterozygous status. The p.G61E mutation is known to cause PCG in a homozygous or compound heterozygous form, and thus, its presence here in a heterozygous form indicates carrier status. These findings suggest that CYP1B1 may have no major role in the pathogenesis of POAG, at least, in the Saudi population. However, further investigations are needed to validate these findings in a larger cohort.