Linkage disequilibrium between glucose-6-phosphate dehydrogenase deficiency and congenital color blindness in Turkish population.

No erythrocyte glucose-6-phosphate dehydrogenase (G6PD)-deficient person was detected among 90 male patients with congenital color blindness (CCB) diagnosed at the Ophthalmology Clinic of our Hospital. Eighteen complete G6PD-deficient subjects had normal color vision. These results suggest that there is a linkage disequilibrium between CCB and G6PD genes.     

The ocular findings in glucose-6-phosphate dehydrogenase deficiency

57 cases with G6PD deficiency and 62 with normal G6PD activities as controls in Chonghua County, Guangdong Province were examined in the respects of visual acuity, color vision, corneal sensitivity, lens, vitreous and fundus. The results showed that the incidences of congenital lenticular opacities and congenital color blindness in G6PD deficiency group were higher than those in the controls. However, there were no findings such as pale conjunctiva, sallow sclera, pallor papillae and macular edema, which could be seen frequently in patients with favism. The hemoglobin values of all the cases were within normal range, which indicated that the subjects with G6PD deficiency usually didn't manifest hemolysis but only had a hereditary susceptibility, and the ocular findings in favism might result from hemolytic anemia, tissue anoxia and unknown toxic substances from vicia faba.     

同一家庭3个姐妹色觉障碍

目的:评价我校医学生和她的家庭成员先天色觉障碍的遗传特征,以建立其遗传模式.方法:运用Ishihara(石原)假同色图试验测定色觉障碍,用FW100色调试验评估其类型.并进行眼科检查和遗传学研究,建立色盲家谱,并对她的家庭给予遗传学咨询.结果:眼科检测结果显示双眼最佳矫正视力为20/20(1.0),近视矫正屈光度-2D,裂隙灯检测和眼压测量结果在正常范围,眼底镜检查视神经、黄斑和周边视网膜均正常,其它外眼评估和神经学检测正常,先证者的姐妹和她父母的眼科检测也正常,3姐妹和父亲的IPPT试验错误得分为19～20/25,结果和红绿色盲中绿色觉异常者一致.染色体分析和卵巢周期均正常.结论:根据她家谱,她的色盲是伴X染色体的隐性外显率模式的遗传特征.     

Glucose-6-phosphate dehydrogenase (G6PD) deficiency in nonarteritic anterior ischemic optic neuropathy in a Sardinian population, Italy

PURPOSE: Glucose-6-phosphate dehydrogenase (G6PD) deficiency is one of the most common human genetic abnormalities, with a high prevalence in Sardinia, Italy. Evidence indicates that G6PD-deficient patients are protected against ischemic heart and cerebrovascular disease and retinal vein occlusion. The purpose of this study was to assess the frequency of G6PD deficiency in Sardinian patients with nonarteritic anterior ischemic optic neuropathy (NAION) and ascertain whether G6PD deficiency may offer protection against NAION. METHODS: Erythrocyte G6PD activity was determined by using a quantitative assay in 140 patients with NAION and 280 age- and gender-matched comparison patients. Conditional logistic regression models were used to investigate the association between G6PD deficiency and NAION. RESULTS: G6PD deficiency was found in 7 (5%) patients with NAION and 34 (12.1%) control subjects. Differences between cases and controls were statistically significant (P = 0.02). Conditional logistic regression analysis, including as covariates G6PD deficiency, hypertension, diabetes, and hypercholesterolemia, revealed that G6PD deficiency was significantly associated with decreased risk for NAION (odds ratio [OR] = 0.4, 95% confidence interval [CI] = 0.17-0.94, P = 0.035). Conditional logistic regression analyses, including systolic or diastolic blood pressure and plasma glucose and cholesterol levels confirmed that G6PD deficiency was associated with a decreased risk for NAION, but the ORs were not significant at the 0.05 significance level (P = 0.085 and P = 0.071). Models including gender x G6PD deficiency interaction disclosed that gender was not an effect modifier of G6PD deficiency (P > 0.20). CONCLUSIONS: The frequency of G6PD deficiency in patients with NAION was significantly lower than expected. Results suggest that G6PD-deficient patients in the Sardinian population have a significantly decreased risk of having NAION.     

Glucose 6-phosphate dehydrogenase deficiency both in red blood cells and lenses of the normal and cataractous native population of Cukurova, the southern part of Turkey. Part I

Glucose 6-phosphate dehydrogenase (G6PD) activity was measured in both red blood cells and lenses of persons with cataracts living in Cukurova, the southern part of Turkey, where G6PD deficiency is well documented. The incidence of red blood cell G6PD deficiency among the patients with cataract (33.3%) was significantly higher than that in individuals with clear lenses (8.2%). The incidence of lens G6PD deficiency in a total of 52 patients with cataract was 52%. Of the lens G6PD-deficient cases, 46.2 and 28.6% of female and male patients, respectively, also showed red blood cell G6PD deficiency.     

Glucose-6-phosphate dehydrogenase deficiency and idiopathic presenile cataract in Dalmatia, Croatia

BACKGROUND: Impaired activity of the enzyme glucose-6-phosphate dehydrogenase (G6PD) has been suggested as a risk factor in cataractogenesis. The aim of this study was to determine the G6PD activity level in 89 male subjects of Dalmatian origin with idiopathic presenile cataracts. METHODS: G6PD activity was determined by a quantitative spectrophotometric method. RESULTS: Of 89 males with presenile cataracts only one (1.1%) had G6PD deficiency. The G6PD deficiency prevalence rate among males with presenile cataracts is not significantly different (p > 0.05) from the prevalence of G6PD deficiency in the general population of Dalmatia (0.75% among men). INTERPRETATION: The results of this study suggest that G6PD deficiency does not represent a pathogenetic factor in presenile cataract, at least not in the population of the southern part of Croatia.     

Glucose-6-Phosphate Dehydrogenase (G6PD) deficiency and senile cataract in a Sardinian male population,Italy

Purpose: There is still no general agreement on the role of G6PD deficiency in the pathogenesis of cataract. The purpose of this study was to determine the prevalence of G6PD deficiency in men with senile cataract from Northern Sardinia, Italy, and to compare it with the prevalence rate of G6PD deficiency in the general population of the same area.

Methods: G6PD activity was determined by using a quantitative method. G6PD blood levels were measured in 1,620 men with cataract. The control group consisted of 1,646 apparently healthy male subjects from the same area. All patients were of Sardinian origin. The Z or Student’s t test was used, when appropriate, to determine differences between groups. The odds ratio (OR) with 95% confidence interval was used to evaluate the association between age-related cataract and G6PD deficiency.

Results: G6PD deficiency was found in 133 (8.2%) out of 1,620 patients with cataract and in 120 (7%) out of 1,646 control subjects. Differences in G6PD prevalence between cataract patients and controls were not statistically significant (P=0.64). There was no age-related statistical difference between G6PD deficient and normal patients with cataract. No statistically significant association between age-related cataract and G6PD deficiency was found (OR=1.14; 95% confidence interval: 0.88–1.47).

Conclusions: The results of this large study suggest that male patients with G6PD deficiency in the Sardinian population do not have a higher risk of developing presenile cataract. G6PD deficiency does not represent a pathogenetic factor for early cataract formation, at least not in the Northern part of Sardinia.     

Glucose-6-phosphate dehydrogenase deficiency in retinal vein occlusion

PURPOSE: Glucose-6-phosphate dehydrogenase (G6PD) deficiency is one of the most common human genetic abnormalities, with a high prevalence in Sardinia, Italy. Evidence indicates that G6PD-deficient patients are protected against ischemic heart and cerebrovascular disease. The purpose of this study was to assess the frequency of G6PD deficiency in Sardinian patients with retinal vein occlusion (RVO) and to ascertain whether the deficiency may offer protection against RVO. METHODS: Erythrocyte G6PD levels were measured in 448 consecutive RVO patients: 194 with central RVO (CRVO) and 254 with branch RVO (BRVO). Age- and sex-matched subjects (n = 896) who were undergoing cataract surgery and had no history of RVO served as the control. Multiple logistic regression models were used to investigate the association between G6PD deficiency and RVO, CRVO, or BRVO. RESULTS: G6PD deficiency was found in 21 (4.7%) patients with RVO, 7 (3.6%) with CRVO, 14 (5.5%) with BRVO, and 107 (11.9%) control subjects. Differences between cases and controls were statistically significant (P < 0.005). Multiple conditional logistic regression analysis, including as covariates G6PD deficiency, hypertension, diabetes, and hypercholesterolemia, revealed that G6PD deficiency was significantly associated with decreased risk of development of RVO, CRVO, or BRVO. After adjustment for hypertension, diabetes, and hypercholesterolemia, the association between G6PD deficiency and RVO, CRVO, or BRVO remained statistically significant. Similar results were obtained after adjustment for systolic or diastolic blood pressure, plasma glucose, and cholesterol levels. However, when the patients with CRVO or BRVO were categorized by gender, a significant association was found only in the women. CONCLUSIONS: The frequency of G6PD deficiency in patients with RVO was significantly lower than expected. The results suggest that G6PD-deficient patients have a significantly decreased risk of development of RVO in the Sardinian population.     

The relationship between glucose-6-phosphate dehydrogenase deficiency and cataracts in Sardinia. An epidemiological and biochemical study

The Italian island of Sardina occupies an important position on the map of glucose-6-phosphate dehydrogenase (G6PD)-deficiency distribution throughout the world, since in this region the condition is particularly frequent and severe (erythrocytes show only 0–7% of G6PD normal activity, while people result affect up to 35% depending on the district). In order to investigate the relationship between the deficiency of G6PD in erythrocytes and in lens, and cataractogenesis, we studied 2125 idiopathic cataractous and non-cataractous subjects, both G6PD-deficient and normal, males and females. Parameters investigated included incidence, distribution and type of cataracts, age at the moment of the first observation, geographical provenance, and G6PD activity in erythrocytes. Moreover, G6PD activity and glutathione (GSSG)-reducing activity was assessed in cataractous lenses obtained from deficient and normal individuals. G6PD deficiency was found to be significantly more frequent in males of the age-group 40–49 years (P = 0.025), while the frequency of G6PD deficiency was decisively lower in the older age-groups. In females, mainly heterozygotes, no evidence of such a relation was found. Cataractous lenses obtained from male patients with no G6PD activity in erythrocytes showed undetectable levels of G6PD activity, and lowered, but not extinguished, levels of GSSG-reducing activity. Cataractous lenses from heterozygous females showed intermediate levels of G6PD activity and GSSG-reducing activity. A preliminary study of 182 diabetic, G6PD-deficient and non-deficient subjects, failed to demonstrate that Sardinian variants of G6PD deficiency provide protection against cataract formation in diabetic patients.     

Congenital achromatopsia: electroretinogram in early diagnosis

PURPOSE: Achromatopsia is a hereditary disease responsible for congenital low vision. Patients present with nystagmus, abnormal visual behavior or photophobia. Only the electroretinogram (ERG) can confirm the diagnosis in infants. PATIENTS AND METHODS: Thirty children referred for nystagmus or low vision were included in this retrospective study. A complete ophthalmological examination, an ERG and when possible a color vision test (Ishihara, Farnsworth 15 Hue test) was done. A Ganzfeld ERG was performed in accordance with ISCEV standards in patients more than 6 years of age. In younger patients, a simplified method using electroluminescent diode stimulation was used and a comparative ERG in accordance with ISCEV standards was performed when the patients were old enough. RESULTS: The ERG response was identical in children and adults. It confirmed the diagnosis of achromatopsia: the scotopic components obtained in dark adapted conditions were normal, (scotopic a-wave, b2 wave). The photopic components, recorded in light-adapted conditions, in order to inhibit the scotopic response (photopic wave, b1 wave), were not recordable. The color vision tests confirmed color blindness; however, in some patients color denomination was correct. CONCLUSION: The simplified ERG procedures performed in our series were reliable in detecting achromatopsia. However, it may not be sufficient to discriminate complete from incomplete achromatopsia.     

Glucose 6-phosphate dehydrogenase deficiency both in red blood cells and lenses of the normal and cataractous native population of Cukurova, the southern part of Turkey. Part II

A possible correlation between development of cataract and glucose 6-phosphate dehydrogenase (G6PD) deficiency in red blood cells and lenses was investigated. The distribution of cataract types in both G6PD-positive and G6PD-deficient patients, the incidence of G6PD deficiency in cortical cataract groups and the distribution of G6PD-deficient cases according to age were determined. The results showed that quite a high percentage of cortical cataractous patients had G6PD deficiency in both red blood cells and lenses.     

Congenital color blindness in young Turkish men

We investigated a healthy population of men from different regions of Turkey for the presence of congenital red-green color blindness. Using Ishihara pseudoisochromatic plates, 941 healthy men from the Turkish army were tested for congenital red-green color blindness. The prevalence of red-green color blindness was 7.33 +/- 0.98% (5.10% protans and 2.23% deutans). These ratios were higher than other reported samples from Mediterranean Europe. Higher percentages of color blindness were found in regions with a lower education level and more consanguineous marriages.     

计算机控制的Ishihara色觉测试法

目的:研究经计算机控制的Ishihara测试法诊断色盲的可靠性及其与经典Ishihara测试法的一致性,计算机控制的Ishihara测试法的敏感性与特异性;并探讨该测试方法在检测先天性色盲或色弱中的潜在价值。方法:用两种方法测试104名大学生的色觉,年龄20～23岁(中位数21岁)。分别采用经计算机控制的Ishihara色板和经典的Ishihara打印色板显露法对个体色觉进行检查。通过上述两种不同的方法评价每个学生对颜色的感知能力,借此探讨计算机控制的Ishihara测试法的特异性,准确性以及与经典法的一致性。结果:本实验共检测到6位男性色盲患者和1位女性色盲患者。调查该女性学生的家族史,发现其母亲为色盲基因携带者,而其父亲为色盲患者。本实验中男性色盲患病率为13.6%(6/44),女性为1.7%(1/60);整个人群总的患病率为6.7%(7/104)。进行本试验前,这些学生并未意识到自己存在色觉功能缺陷。为探讨这两种方法的一致性,分别对色觉正常和患色盲的学生的测试结果进行比较。结果表明:两种实验方法的特异性及敏感性均为100%,一致性达到100%。结论:计算机控制的Ishihara测试法是数字调控性的,但有关色觉测试的基本概念没有改变。该法总的测试时间和误差计分都已标准化,与手动测试法相比有明显的优势;而且该法与被认为是"金标准"的经典测试法的一致性达到100%。这些特征表明,计算机控制的Ishihara测试法是一种新颖和可靠的方法。     

The Study of G6PD in Erythrocyte and Lens in Senile and Presenile Cataract

The G6PD activity of erythrocytes in 113 male patients with senile and presenile cataract and 86 controls, and G6PD activity of lens in 30 patients with senile cataract and 42 controls were reported. The cataractous group had higher frequency of G6PD deficiency and lower average G6PD level in erythrocytes and lenses, but with out statistical significance. The frequency of G6PD deficiency of erythrocytes in presenile cataractous group was higher than that of senile cataractous group but with no statistical significance too. However, the average G6PD level of erythrocytes in presenile cataractous group was lower than that of senile cataractous group and with statistical significance (P<0.05). The G6PD activity of lenses only presenile in the cortex and have a positive correlation with that of erythrocytes. There was a case with deficiency of G6PD both of erythrocytes and cataractous lenses in both eyes. The results indicate that the deficiency of G6PD might be one of the cataractous pathogenetic factor for presenile cataract. Measurement of G6PD activity of erythrocytes among population might be of significance in finding the risk factor for cataract.     

Glucose-6-phosphate dehydrogenase deficiency and incidence of cataract in Sicily

The incidence of G6PD deficiency in red blood cells of 241 Sicilian cataractous patients (138 males and 103 females) and in the lens of 32 subjects (15 males and 17 females) of the same group was evaluated. The incidence of G6PD deficiency was significantly higher than expected (p<0.001), both in RBCs and in lens. The results suggest that G6PD deficiency is a risk factor for cataract both in hemizygous males and heterozygous females.     

Decreased Glucose-6-PhosphateDehydrogenase (G6PD) Activity and Risk of Senile Cataract in Taiwan

G6PD deficiency may render afflicted individuals more susceptible to certain degenerative diseases. To clarify the relationship between G6PD deficiency and cataract, blood G6PD activity was determined in patients with cataract in Taiwan. The cases and hospital-based controls were recruited from the medical outpatient department and from the physical checkup department at Chang Gung Memorial Hospital, respectively. A questionnaire survey was used to determine associations between cataracts and their risk factors. G6PD activity in fresh RBC was quantitatively measured and genomic DNA was extracted from lymphocyte nuclei. The mean blood G6PD activity among cataract patients (278.1 U/10 RBC) was similar to that of normals (288.0 U/10 RBC). No statistically significant difference in the distribution of G6PD activities as grouped by an increment of 100 U/ RBC was observed between cataract patients and normal subjects. The predominant forms of G6PD gene mutation (cDNA 1376 G to T and 95 A to G) were both found in the patients with cataract. The adjusted odds ratio for cataract was 1.21 for every decrement of 100 U/10 RBC of G6PD activity in these subjects. These data indicate that G6PD activity is not a potential risk factor for senile cataract in Taiwan.     

Decreased glucose-6-phosphate-dehydrogenase (G6PD) activity and risk of senile cataract in Taiwan

G6PD deficiency may render afflicted individuals more susceptible to certain degenerative diseases. To clarify the relationship between G6PD deficiency and cataract, blood G6PD activity was determined in patients with cataract in Taiwan. The cases and hospital-based controls were recruited from the medical outpatient department and from the physical checkup department at Chang Gung Memorial Hospital, respectively. A questionnaire survey was used to determine associations between cataracts and their risk factors. G6PD activity in fresh RBC was quantitatively measured and genomic DNA was extracted from lymphocyte nuclei. The mean blood G6PD activity among cataract patients (278.1 U/10[12] RBC) was similar to that of normals (288.0 U/10[12] RBC). No statistically significant difference in the distribution of G6PD activities as grouped by an increment of 100 U/[10, 12] RBC was observed between cataract patients and normal subjects. The predominant forms of G6PD gene mutation (cDNA 1376 G to T and 95 A to G) were both found in the patients with cataract. The adjusted odds ratio for cataract was 1.21 for every decrement of 100 U/10[12] RBC of G6PD activity in these subjects. These data indicate that G6PD activity is not a potential risk factor for senile cataract in Taiwan.     

Management of congenital elevation deficiency due to congenital third nerve palsy and monocular elevation deficiency

Purpose: To document the presentation and management of congenital III nerve palsy and monocular elevation deficiency to single ophthalmologist over a 14‐year period. Surgical management was reviewed and visual outcome was analysed. Methods: A retrospective study was conducted of all patients presenting during a period between 1992 and 2006 to the private practice of a paediatric ophthalmologist, with either congenital III or monocular elevation deficiency. For patients requiring surgical intervention pre‐ and post‐surgical data were documented and analysed. Results: A total of 19 congenital III and 13 monocular elevation deficiency patients were identified. There were eight surgical patients in each congenital III nerve palsy group and in the monocular elevation deficiency group. The congenital III group had a preoperative mean exotropia for near of −36 prism dioptres (PD) compared with postoperative mean exotropia for near −16 PD. Preoperative mean hypotropia for near of −19 PD was improved to postoperative mean hypotropia of −5 PD. The monocular elevation deficiency group had preoperative mean esotropia for near of +6 PD compared with postoperative mean exotropia for near −5 PD. Preoperative mean hypotropia for near of −15 PD was improved to postoperative mean hypotropia of −7 PD. At last follow up both groups had a majority of mild or no amblyopia noted. Conclusion: Superficially, congenital III and monocular elevation deficiency may appear similar, both frequently having ptosis and hypotropia as features. Careful clinical assessment of the horizontal alignment and the result of forced duction testing will usually allow them to be distinguished. Congenital III more frequently requires surgery for exotropia as well as surgery for hypotropia and monocular elevation deficiency more often requires surgery just for hypotropia. The ptosis surgery is similar for either diagnosis in this study. Significant cosmetic improvement, as well as excellent visual acuity outcomes can be achieved.     

伊朗女中学生色觉缺失的患病率(英文)

色盲是常见病,先天性色盲X连锁隐性遗传。我们的研究中,随机分组抽样1600个女学生,进行Ishihara假同色表检查。其中0.63%色觉缺失,其中6例绿色弱(0.38%),4例红色弱(0.25%)。     

Evaluation of children in six blind schools of Andhra Pradesh

PURPOSE: 1. To determine the anatomical site and underlying causes of severe visual impairment and blindness in children in special education in Andhra Pradesh, India. 2. To compare the causes of blindness in two different regions in the state. 3. To evaluate improvement with correction of refractive error and low-vision devices (LVDs). METHODS: Children in 6 schools for the blind and in 3 integrated education programmes were examined by one ophthalmologist, and were refracted and assessed for LVDs by an optometrist. The major anatomical site and underlying aetiology of severe visual impairment and blindness (SVI/BL; < 6/60 in the better eye) were recorded using the standardised WHO reporting form. RESULTS: Two hundred and ninety one students under 16 years were examined, and after refraction, 267 (91.7%) were classified as being severely visually impaired or blind. The most common anatomical sites of SVI/BL were retina in 31.1% children; cornea in 24.3%; and whole globe in 20.2%. The aetiology was unknown in 38.2%, hereditary in 34.8% and childhood causes in 24%. 114 children (39.2%) had functional low vision (i.e. visual acuity < 6/18 to light perception with navigational vision). In this group, 36 children improved with spectacles and 16 benefited by LVDs. 41 children (15.4%) were able to read N10 point though they were studying Braille. CONCLUSION: Overall 37.4% of children had "avoidable" causes of blindness. The major avoidable causes were vitamin-A deficiency and cataract. Vitamin-A deficiency and congenital anomalies were more common in the dry plateau areas of the state. One in seven children could read normal print with optical support.