Tomihiko Tanino

Phenotype of cytochrome P4501B1 gene (CYP1B1) mutations in Japanese patients with primary congenital glaucoma

Aim: To investigate the phenotypes associated with cytochrome P4501B1 gene (CYP1B1) mutations in Japanese patients with primary congenital glaucoma (PCG). Methods: 66 Japanese patients with PCG were screened for sequence mutations in the CYP1B1 gene using single strand conformation polymorphism analysis followed by automated DNA sequencing. 11 cases had a CYP1B1 mutation in both alleles (the mutation group) and 21 cases did not have a CYP1B1 mutation (the “no mutation” group). The clinical features, such as age of onset, sex, intraocular pressure, and Descemet‘s membrane rupture, of the two groups were compared. Results: The clinical symptoms and signs did not differ for the two groups. The mean age at onset was 1.7 months in the mutation group and 3.1 months in the no mutation group, and the male:female ratio was 6:5 in the mutation group and 19:2 in the no mutation group. Both of these differences were statistically significant. Conclusions: In clinically diagnosed cases of PCG, a subgroup shows a CYP1B1 gene mutation. Age at onset was earlier in PCG patients with CYP1B1 mutations than in patients without mutations. Women were more prevalent among patients with mutations than those without mutations.

Scanning laser Doppler flowmeter study of retinal blood flow in macular area of healthy volunteers

Aim: To compare the interocular and intraocular differences of capillary perfusion, and the intraocular regional differences of retinal blood flow in the macular area of healthy volunteers. Methods: Tissue blood flow in the macula was examined in both eyes of 20 healthy volunteers with the Heidelberg retinal flowmeter. Blood flow measurements were made in a 10°×2.5° area superior and inferior to the macula. The mean blood flow (MBF) was calculated by an automatic full field perfusion image analyser program. The MBF in the right and left eyes and in the superior and inferior macular areas of the same eye were compared. Results: The ratios of the MBF in the right eye to the left eye in the macular areas were 1.00, and 1.03, respectively. The ratio of the MBF in the superior macular area to the inferior area was 1.01 for the right eyes and 1.04 for the left eyes. Conclusions: Because no significant differences were found in the MBF between the two eyes and between the superior and inferior macular areas in the same eye, interocular (for example, affected eye versus fellow eye) and intraocular (superior versus inferior macular areas) comparisons of MBF can be made to determine if changes in retinal perfusion have occurred.

Novel Mutations in the Myocilin Gene in Japanese Glaucoma Patients

Myocilin is a gene responsible for juvenile onset primary open angle glaucoma (POAG) mapped as the GLC1A locus and, many mutations have been reported worldwide. Some mutations were found not only in patients with juvenile onset POAG, but also in patients with late onset POAG and in patients with normal tension glaucoma. To investigate the mutation prevalence in Japan, we performed a mutation analysis in 140 unrelated Japanese patients. We have identified the 10 sequence variants, of which four were highly probable for disease‐causing mutations (Arg46ter, Arg158Gln, Ile360Asn, and Ala363Thr), and six polymorphisms (Gln19His, Arg76Lys, Asp208Glu, Val439Val, Arg470His, and Ala488Ala). Thus, myocilin mutations were found at the rate of 4/140 (2.9%) probands, similar to previous reports with other ethnic populations. Hum Mutat 16:270, 2000.

Effect of topical unoprostone isopropyl on optic nerve head circulation in controls and in normal-tension glaucoma patients.

PurposeTo evaluate the effect of unoprostone isopropyl on microcirculation in the optic nerve head (ONH) of controls and patients with normal-tension glaucoma (NTG).MethodsThirty healthy volunteers were randomly placed in a placebo group or a control group. For ten NTG patients, one eye was selected to receive the placebo drops and the contralateral eye received the unoprostone in a masked fashion. In both studies, the intraocular pressure (IOP) and the parameters of the blood hemodynamics of the ONH were obtained before and at 1 and 2 h after the instillation. Blood flow measurements were made with a scanning laser Doppler flowmeter.ResultsIn both control subjects and NTG patients, the changes in the IOPs after the instillation of either unoprostone or the placebo were not significant because almost all of the NTG patients had IOPs lower than 15 mmHg. Although the hemodynamic parameters were not significantly changed in the placebo-treated eyes of the controls, the eyes of the controls treated with unoprostone had mean blood velocity and flow values that were significantly higher than the baseline values 1 and 2 h after instillation (P < 0.01). The velocity values of the controls treated with unoprostone were significantly higher than in those controls receiving the placebo at 2 h postinstillation (P = 0.027). The values for the three circulation parameters (volume, velocity, flow) were significantly higher than the baseline values after instillation in the eyes of the NTG patients treated with unoprostone (P < 0.05). In contrast, none of these parameters was significantly different from the baseline in the eyes of NTG patients treated with placebo.ConclusionsThese results showed that unoprostone significantly increased microcirculation in the ONH in control subjects and in NTG patients without reducing the IOP significantly. Jpn J Ophthalmol 2005;49:287–293

Variants of the Myocilin Gene in Japanese Patients with Normal-Tension Glaucoma

Myocilin (MYOC) mutations are associated with juvenile- and adult-onset primary open-angle glaucoma (POAG). The purpose of this study was to determine whether MYOC gene mutations are associated with normal-tension glaucoma (NTG). The prevalence of MYOC mutations was determined in 80 Japanese NTG patients and 100 control subjects. In addition, the expression of mutant MYOC was determined by transforming COS-1 cells with five myocilin variants (R158Q, D208E, I360N, A363T, and I477S) and examining whether myocilin was present in the cultured cells and/or the culture medium by western blotting. Six different nucleotide sequence variants, R46Stop, R76K, R158Q, D208E, A488A, and one in the 3′ non-coding region, were identified in 80 NTG patients. Variants in codon 46 (R46Stop), codon 158 (R158Q), and codon 488 (A488A) were not found in the 100 normal controls. The frequency of other sequence changes (R76K, D208E, and 3′ non-coding) in NTG patients did not differ significantly from the frequencies in the control subjects. COS-1 cells transfected with the wild type, R158Q, or D208E variants secreted myocilin into the culture medium. On the other hand, the detected myocilin was significantly reduced in the medium of cells transfected with the I360N, A363T, or I477S variants that were previously identified as mutations for POAG. Definitive evidence of MYOC variants associated with NTG was not found.

Novel myoc Gene Mutation, Phe369leu, in Japanese Patients with Primary Open-angle Glaucoma Detected by Denaturing High-performance Liquid Chromatography

Purpose:To screen for mutations in the MYOC gene in Japanese patients with primary open-angle glaucoma (POAG) using denaturing high-performance liquid chromatography (DHPLC). Patients and Methods:Blood samples were collected from 171 patients with POAG and 100 controls from seven institutions in Japan. For high-throughput analysis, seven exonic regions were amplified by polymerase chain reaction using DNA pooled from three patients; each DNA pool was then analyzed chromatographically. For analysis of a small number of samples, 7 exonic regions were amplified separately but simultaneously with annealing at 58°C in each patient and then chromatographed, using 7 wells of the same 96-well plate per sample. When chromatographic patterns were abnormal by either method, the PCR products of the individual samples were sequenced. Results:Four glaucoma-causing mutations were identified in five POAG patients (2.9%). One missense mutation, Phe369Leu, is new; and three others, Ile360Asn, Ala363Thr, and Thr448Pro, have been reported in Japanese patients. Phe369Leu was associated with adult onset POAG. Conclusions:Mutations in the MYOC gene were demonstrated chromatographically in 2.9% of our Japanese POAG patients. The use of pooled DNAs with DHPLC analysis is a time- and labor-saving technique. All mutations detected appear to be specific to Japanese patients.

[A comparison of visual field and optic disc appearance depending on the peak intraocular pressure in patients with normal-tension glaucoma].

PurposeTo investigate the clinical differences between the two groups depending on the peak intraocular pressure (IOP) in patients with normal-tension glaucoma (NTG).MethodsWe studied 96 eyes of 48 NTG patients who were hospitalized for diurnal IOP measurement. Then we selected the eye with peak IOP higher than the other, or the right eye if the peak IOP of both eyes was equal. We divided these eyes into a “high-teen” group (peak IOP ≧ 16 mmHg) and a “low-teen” group (peak IOP ≦ 15 mmHg). We compared these two groups by age, gender, refraction, IOP, visual field defect, optic disc appearance, and tomograph. We used a Humphrey C30-2 program to estimate the visual field defect and classified the optic disc into four types according to Nicolela’s criteria. 22 eyes were imaged with Heidelberg Retina Tomograph® (HRT) to obtain topographic parameters of the optic disc.ResultsThere were no significant differences in age, gender, refraction, optic disc appearance, or tomograph between two groups. The trough and variation range of diurnal IOP were significantly larger in the high-teen group (p ≪ 0.01). The value of mean deviation (MD) given by STATPAC was statistically lower in the high-teen group (p ≪ 0.01).ConclusionsIn patients with NTG, the visual field damage tended to be greater in the high-teen group than in the low-teen group. We surmise that the IOP might influence the progression of visual field defect in NTG. Nippon Ganka Gakkai Zasshi (J Jpn Ophthalmol Soc 107:433–439, 2003)