Choroidal hemodynamic in myopic patients with and without primary open‐angle glaucoma

Purpose: To investigate the change in subfoveal choroidal blood flow in patients with glaucoma and to assess the effect of myopia, as one of the vascular risk factors for glaucoma on this flow. Methods: Subfoveal choroidal blood flow in groups of 12 myopic and glaucomatous eyes has been investigated by means of the laser Doppler flowmetry (LDF), comparing the results with those of 17 myopic eyes without glaucoma, 34 non‐myopic glaucomatous eyes and of 50 control eyes. The subfoveal choroidal LDF parameters, that is, blood velocity (ChBVel), volume (ChBVol), and flow (ChBF), as well as the vascular resistance were studied in each group. Statistical analysis was performed by means of anova and t‐test according to the Bonferroni procedure for multiple comparisons. Pearson correlation was used to establish the correlations between the hemodynamic parameters and the degree of myopia in dioptres. Results: All LDF parameters (ChBVel, ChBVol and ChBF) were significantly reduced in glaucomatous patients (1.3 ± 0.4, 0.14 ± 0.06 and 4 ± 2 respectively) and myopic patients with primary open‐angle glaucoma (POAG) (1.3 ± 0.4, 0.08 ± 0.04 and 2 ± 0.7 respectively) and without POAG (1.2 ± 0.3, 0.11 ± 0.08 and 2 ± 1 respectively) in comparison with age‐matched controls (1.5 ± 0.4, 0.27 ± 0.1 and 8 ± 2 respectively). On the other hand, the choroidal vascular resistance (Rm) was increased in the previously described studied patients groups (16 ± 7, 26 ± 9 and 24 ± 9 respectively) compared with controls (7 ± 2). The LDF parameters did not differ significantly between myopic subjects without and with POAG (p = 0.09, p = 0.09, p = 0.2, p = 0.08 and p = 0.9 respectively). Compared to patients with emmetropic glaucomatous, significant reduction in the ChBVol and ChBF and increased Rm were recorded in patients with glaucomatous myopia (p = 0.05, p = 0.04 and p = 0.04 respectively). Pearson correlation demonstrated a significant correlation between the degree of myopia in dioptres and the ChBF (p = 0.012). Conclusions: The subfoveal choroidal LDF parameters were reduced in patients with POAG and myopia. Theses alterations are more in glaucomatous patients with myopia in comparison with age‐matched glaucomatous patients without myopia. These data suggest that the impaired choroidal circulation caused by myopia might be an important additional risk factor involved in the glaucomatous damaging process.     

原发性先天性青光眼患者CYP1B1突变的研究

目的:了解原发性先天性青光眼患者致病基因CYP1B1(Cytochrome P450 family 1 subfamily B polypeptide 1)的变异情况.方法:采用高分辨率熔解(high-resolution melting,HRM)方法,分析20例原发性先天性青光眼患者的CYP1 B1基因热点突变区,同时采用测序的方法验证HRM的检测结果.结果:检出g.6767C＞T(p.D449D)变异2例,g.2527C＞G(p.R48G)变异1例,两种变异共存者1例.结论:在CYP1B1基因突变筛查方法中,HRM具有高度的灵敏性和特异性,可用于筛查原发性先天性青光眼.PCG的原因可能与g.6767C＞T(p.D449D)和g.2527C＞G(p.R48G)的变异有关;两种变异共存者可能导致更严重的PCG.     

Compound heterozygous mutations in CYP1B1 gene leads to severe primary congenital glaucoma phenotype

AIM: To identify the novel mutation alleles in the CYP1B1 gene of primary congenital glaucoma (PCG) patients at Shandong Province of China, and investigate their correlation with glaucomatous features. METHODS: The DNA from the peripheral blood of 13 congenital glaucoma patients and 50 ethnically matched healthy controls from the affiliated hospital of Qingdao University were extracted. The coding region of the CYP1B1 gene was amplified by PCR and direct DNA sequencing was performed. Disease causing-variants were analyzed by comparing the sequences and the structures of wild type and mutant CYP1B1 proteins by PyMOL software. RESULTS: Two missense mutations, including A330F caused by c.988G>T&c.989C>T, and R390H caused by c.1169G>A, were identified in one of the 13 PCG patients analyzed in our study. A330F mutation was observed to be novel in the Chinese Han population, which dramatically altered the protein structure of CYP1B1 gene, including the changes in the ligand-binding pocket. Furthermore, R390H mutation caused the changes in heme-protein binding site of this gene. In addition, the clinical phenotype displayed by PCG patient with these mutations was more pronounced than other PCG patients without these mutations. Multiple surgeries and combined drug treatment were not effective in reducing the elevated intraocular pressure in this patient. CONCLUSION: A novel A330F mutation is identified in the CYP1B1 gene of Chinese PCG patient. Moreover, in combination with other mutation R390H, this PCG patient shows significant difference in the CYP1B1 protein structure, which may specifically contribute to severe glaucomatous phenotype.     

Two novel variants in CYP1B1 gene: a major contributor of autosomal recessive primary congenital glaucoma with allelic heterogeneity in Pakistani patients

AIM: To find the CYP1B1 mutations associated with primary congenital glaucoma (PCG) in Pakistani consanguineous pedigrees. METHODS: After getting informed consent, 11 consanguineous pedigrees belonging to different ethnic groups were enrolled. Detailed medical history was recorded and pedigrees were drawn. The standard ophthalmological examination was done to characterize the phenotype. Genomic DNA was extracted from 10 mL whole blood and coding exons and exon intron boundaries of CYP1B1 gene were directly sequenced. Bioinformatics tools were used to model the mutant protein and predict the effect of novel variants on protein structure and function. RESULTS: Sequencing analysis revealed 5 different CYP1B1 variants in 7 families (7/11; 64%), including two novel variants. A common mutation, p.R390H was found in four families, whereas p.P437L was found once in a family. Two novel variants, a homozygous non sense variant p.L13* and a compound heterozygous variant, p.P350T along with p.V364M were segregating with PCG in two families. All the patients had the variable onset and severity of the disease. The success rate of early clinical interventions was observed dependent on mutation types and position. Two different haplotypes were associated with frequently found mutation, p.R390H. CONCLUSION: Identification of novel CYP1B1 variants reassert the genetic heterogeneity of Pakistani PCG patients. The patients with missense mutations show severe phenotypic presentations and poor vision after surgical interventions as compare to patients with null variants. This may help to better understand the role of CYP1B1 mutations in the development of PCG and its course of pathogenicity.     

湖北地区汉族原发性先天性青光眼患儿CYP1B1基因突变分析

目的研究湖北地区汉族原发性先天性青光眼(primary congenital glaucoma,PCG)患儿CYP1B1基因的突变情况。方法用苯酚-氯仿法从38例原发性先天性青光眼患儿的全血细胞中提取基因组DNA。然后通过聚合酶链反应-单链构象多态性(single-strand conformation polymorphism,PCR-SSCP)银染色法检测CYP1B1基因第2、3外显子的突变情况。结果5例PCG患儿检出CYP1B1基因第3外显子异常DNA片段条带,经测序分析证实为7990C→T,未发现第2外显子存在基因突变。结论CYP1B1基因具有明显的遗传异质性。应用PCR-SSCP技术可初步筛查原发性先天性青光眼患儿CYP1B1基因突变。     

CYP1B1突变与眼科疾病

细胞色素P4501B1（CYP1B1）是人体重要的代谢酶，本文从生化结构、细胞定位、遗传多态等方面对P4501B1基因（CYP1B1）进行了综述，并重点讨论了该基因的突变在原发性先天性青光眼、青少年型青光眼、Peters异常等眼病中的可能致病机制。     

Frequency of systemic vascular diseases in patients with primary open‐angle glaucoma and exfoliation glaucoma

Purpose: Abnormal fibrils can be identified by electron microscopy in the heart, lung, liver, kidney, cerebral meninges and other tissues of patients with exfoliation syndrome (ES). However, a clinical association of ES with arterial hypertension (HT), ischaemic heart disease (IHD), cerebrovascular accidents and aneurysm of the abdominal aorta is debated. We conducted a national registry‐based survey to further assess the first two of these associations. Methods: We reviewed the records of 519 consecutive patients to whom the Social Insurance Institution of Finland had granted free medication for glaucoma according to national common criteria. The glaucoma was classified either as primary open‐angle glaucoma (POAG) or exfoliation glaucoma (EG), masked to any systemic diseases; 20 patients with other types of glaucoma were excluded from the survey. Masked to the type of glaucoma, the registry provided data on free medication similarly granted for HT, IHD and diabetes mellitus (DM), a known modifier of risk for cardiovascular disease. Data were analysed by logistic regression, modelling age, gender and DM as confounders. Results: The control group of 344 patients with POAG was comparable as regards gender with the study group of 155 patients with EG, but patients with POAG were both younger (mean 69 versus 73 years; P < 0.0001) and had DM twice as often (10% versus 5%; P = 0.05) compared to those with EG. Adjusting for age, gender and presence of DM, no difference in frequency of HT [odds ratio (OR) 0.80 for presence of EG; 95% confidence interval (CI) 0.52–1.23, P = 0.31] or IHD (OR 0.86 for presence of EG; 95% CI 0.49–1.13, P = 0.66) was detected between the two groups. Conclusion: In this population‐based registry survey, no difference in frequency of HT or IHD was noted between patients with POAG and EG who had been granted free medication for these chronic diseases according to national common criteria. The frequency of DM was lower among patients with EG, in line with several previous reports.     

Overview of Cytochrome P450 1B1 gene mutations in patients with primary congenital glaucoma

The objective of this study was to investigate the distribution of mutations in the Cytochrome P450 1B1 gene (CYP1B1) in patients with primary congenital glaucoma (PCG) among different populations. All identifiable original studies on CYP1B1 gene mutations of patients with PCG were reviewed. Finally, DNA mutations within the CYP1B1 gene were identified in 542 patients with PCG according to 52 scientific articles and 147 distinct mutations were found. The 3987G>A (G61E) missense mutation is a founder mutation in Middle Eastern population, responsible for 45.52% of CYP1B1 mutations. In Gypsies, missense mutation 7996G>A (E387K) seems to be a founder mutation, accounting for 79.63% of CYP1B1 mutations. It seems that there is no founder mutation in Asian or Caucasian population, but also accumulates in some spots. Mutations 7927G>A (V364M), 7990C>T (L385F) and 8006G>A (R390H) are common in Asian population. In Caucasians, 7940G>A (R368H), 8037dup10, 8006G>A (R390H), 7901del13, 4340delG, 3987G>A (G61E), 7996G>A (E387K), 4490G>A (E229K) and 8005C>T/A (R390C/S) are common mutations. The findings suggest that ethnic differences and the geographical distribution of PCG may be associated with different CYP1B1 mutation patterns. Such information may be useful in developing strategies for reliable clinical genetic testing of patients with PCG and their families.     

原发性先天性青光眼CYP1B1基因变异初步研究

目的了解CYP1B1基因变异在中国原发性先天性青光眼(PCG)患者发病中的作用。方法收集来自不同地区的16例PCG患者,对其CYP1B1基因编码外显子进行直接测序,对照组进行单核苷酸多态性分析。结果在1例PCG患者中发现了一种变异,为8006G>A(R390H)。它是位于外显子III的错义突变。还发现了五种单核苷酸多态性,分别为3793T>G,R48G,A119S,A330S,V432L。结论CYP1B1基因是导致中国人PCG患者的致病基因,但也有其他变异可能和PCG变异有关。     

Mitomycin‐C‐augmented deep sclerectomy in patients with primary open‐angle glaucoma and exfoliation glaucoma: a 1‐year prospective study

Purpose: To investigate the efficacy and safety of mitomycin C (MMC)‐augmented deep sclerectomy with implant (DSCI) in patients with primary open‐angle glaucoma (POAG) and exfoliation glaucoma (ExG). Methods: A total of 68 eyes of 68 patients with POAG and ExG were enrolled consecutively to undergo DSCI with MMC (0.4 mg/ml for 2 min). The intraocular pressure (IOP), number of antiglaucoma medications, neodymium:yttrium‐aluminum‐garnet (Nd:YAG) laser goniopunctures and complications were compared postoperatively. Surgery was considered as a complete success when IOP was < 18 mmHg without antiglaucoma medication. Results: Preoperatively, the mean IOPs were 23.1 ± 5.8 and 25.4 ± 8.3 mmHg, and 13.8 ± 6.1 and 11.2 ± 5.6 mmHg in the POAG and ExG groups, respectively, at 12 months. 77.4% and 75.7% of surgeries were a complete success in the POAG and ExG groups, respectively [not significant (NS)]. Five patients (16.1%) in the POAG group but none in the ExG group (0%) were receiving antiglaucoma medication at 12 months (NS). Nd:YAG laser goniopuncture was performed in 29.0% of eyes in the POAG group and in 55.6% of eyes in the ExG group (p = 0.047). Postoperatively, choroidal detachment occurred in 16.1% of eyes in the POAG group and in 10.8% of eyes in the ExG group (NS). We encountered no serious complications related to MMC use. Conclusion: DS with MMC augmentation appears to be equally effective in ExG and POAG patients in lowering IOP to target levels, at least in the short term, with few immediate postoperative complications.