Another seemingly popular glucose-6-phosphate dehydrogenase deficiency related research area is in cataractogenesis, the formation of cataracts. The idea that cataractogenesis and glucose-6-phosphate dehydrogenase deficiency are linked was first proposed by Zinkham in 1961. 7. 22.In the normal healthy lens, glucose-6-phosphate dehydrogenase is involved in a series of activities which are not clearly known yet. But what is known is that glucose-6-phosphate dehydrogenase is indispensable for the growth of lens cells and the maintenance of transparency. It has been demonstrated time and again in independent studies that a person with genetically determined deficiency of glucose-6-phosphate dehydrogenase may be more susceptible to cataract formation, at least for those cases with severe degree of the enzyme deficiency. 7. 23. 24.Conversely, some other studies pointed otherwise. Studies done in Thailand in the 1980's 7.and in Sardinia, an Italian island by Meloni in 1990 22.failed to demonstrate any difference in the incidence of cataract in persons with glucose-6-phosphate dehydrogenase deficiency compared to normal healthy individuals.
The cells of the mammalian lens have many properties in common with the red blood cell. 25.This underlines the argument of the importance of glucose-6-phosphate dehydrogenase in maintaining the levels of reduced NADPH available for preventing the oxidation of sulfhydryl (-SH) groups in lenticular cells. In glucose-6-phosphate dehydrogenase deficiency there is a decreased synthesis of ribose and a lower turnover of proteins. Coupled with the low levels of reduced glutathione, this might reduce the solubility of membrane proteins exposed to oxidative stress. Following this, high molecular weight protein (S-S) aggregates are believed to form in the lens and cause cataract development. 7. 22. 25.
Before jumping to any conclusions though on the existence of a positive relationship between the tendency of cataractogenesis and glucose-6-phosphate dehydrogenase deficiency, we must bear in mind that cataract is a common disease with several known etiologic factors, namely hereditary, latitude and exposure to light. 22.
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Prepared on 01 Jan 2008 by teekoonhien |
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