A group of researchers with the Ocular Genomics Institute analyzed a 1984-1991 study on the effects of vitamins A and E on retinitis pigmentosa to look for any biological correlations and modifiers to the original study’s results. The researchers sequenced DNA samples that had been recovered from many of the participants and used existing information from other participants to see what genetic mutations were present. Researchers also used implicit time, the time between light hitting the eye and the retina responding, to predict the severity of retinitis pigmentosa progression - a measure that had not been used in the original study. The original study had shown benefit from Vitamin A and adverse effects from Vitamin E. The Ocular Genomics Institute group included additional data that had not been included in the original study, added vitamin A data from a subsequent study for a greater sample size, and used new analyses to determine a biological basis for effects. They found that with the implicit time prediction and additional data, there was no statistically significant effect from Vitamin A and a slightly decreased negative effect from Vitamin E compared to the original study.
What this means for Usher syndrome: This updated analysis reiterates the relevance of different genetic mutations and symptom presentations in retinitis pigmentosa and Usher syndrome. It also shows that Vitamin A supplementation is not effective enough on disease progression to be recommended, whereas Vitamin E should still be avoided. This research also suggests that other therapies need to be developed to slow the progression of retinitis pigmentosa in Usher syndrome.
