Cataracts in glucose-6-phosphate dehydrogenase deficiency

Glucose-6-phosphate dehydrogenase--beyond the realm of red cell biology

Glucose-6-phosphate dehydrogenase (G6PD) is critical to the maintenance of NADPH pool and redox homeostasis. Conventionally, G6PD deficiency has been associated with hemolytic disorders. Most biochemical variants were identified and characterized at molecular level. Recently, a number of studies have shone light on the roles of G6PD in aspects of physiology other than erythrocytic pathophysiology. G6PD deficiency alters the redox homeostasis, and affects dysfunctional cell growth and signaling, anomalous embryonic development, and altered susceptibility to infection. The present article gives a brief review of basic science and clinical findings about G6PD, and covers the latest development in the field. Moreover, how G6PD status alters the susceptibility of the affected individuals to certain degenerative diseases is also discussed.

Bilateral cataracts associated with glucose-6-phosphate dehydrogenase deficiency

Glucose-6-phosphate dehydrogenase (G6PD) has an essential role in the defense against cellular oxidative injury. In neonates, the most common manifestation of G6PD deficiency is jaundice and hemolysis due to factors causing oxidative stress. Less known are the ocular associations described with G6PD deficiency, including cataracts. Oxidative injury is involved in the pathogenesis of almost all forms of cataracts, causing the lens proteins to undergo modifications, denaturation and form insoluble aggregates resulting in cataracts. Although cataracts in adult males have been reported in several studies, there are few reports of cataracts in infants with G6PD deficiency. We describe a preterm male neonate with G6PD deficiency who developed bilateral cataracts following an episode of neonatal sepsis and severe hemolysis necessitating an exchange blood transfusion.

Glucose-6-phosphate dehydrogenase--from oxidative stress to cellular functions and degenerative diseases

Glucose-6-phosphate dehydrogenase (G6PD), the first and rate-limiting enzyme of the pentose phosphate pathway, is indispensable to maintenance of the cytosolic pool of NADPH and thus the cellular redox balance. The role of G6PD as an antioxidant enzyme has been recognized in erythrocytes for a long time, as its deficiency is associated with neonatal jaundice, drug- or infection-mediated hemolytic crisis, favism and, less commonly, chronic non-spherocytic hemolytic anemia. To a large extent, advances in the field were made on the pathophysiology of G6PD-deficient erythrocytes, and the molecular characterization of different G6PD variants. Not until recently did numerous studies cast light on the importance of G6PD in other aspects of the physiology of both cells and organisms. Deficiency in G6PD activity, and hence a disturbance in redox homeostasis, can lead to dysregulation of cell growth and signaling, anomalous embryonic development, altered susceptibility to viral infection as well as increased susceptibility to degenerative diseases. The present review covers recent developments in this field. Additionally, molecular characterization of G6PD variants, especially those frequently found in Taiwan and Southern China, is also addressed.

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.