Surveying the Health of People with Choroideremia
Report from the annual ARVO (Association for Research in Vision and Ophthalmology) meeting
May 4, 2011 - Choroideremia is an X-linked inherited retinal degenerative disease. Because the mutated gene that causes choroideremia is located on the X chromosome, it is far more common in men than in women. Female carriers (who have one normal gene and one with a mutation) may develop milder symptoms, and their sons are at risk of inheriting the mutated gene and developing the disease.
Dr. Ian MacDonald, of the University of Alberta, is a world-leading authority on choroideremia. He developed the first practical screening test for it, with the support of FFB donors.
Recently, Dr. MacDonald and his colleagues conducted an online survey to learn more about the factors that affect the health of people with choroideremia. This survey was available on the FFB website and a number of other sites for much of last year, and Dr. MacDonald presented some of the survey findings at ARVO 2011.
Nearly 200 people answered this survey completely enough for Dr. MacDonald’s team to analyse. The respondents included over 115 affected men (men with choroideremia), about 50 women who are carriers of the disease, and 20 unaffected men whose brothers have choroideremia.
This survey results may not be a completely faithful represention of all people with choroideremia, but they did highlight some potential health issues.
Although vision loss in female carriers has usually been considered rare, about 30% of the women who responded had some symptoms. This finding suggests that women in affected families should be followed more closely for signs of disease and tested genetically.
In general, people in this study were no more likely than other North Americans to have systemic health problems (like arthritis or heart disease). However, men who were blind due to choroideremia were more likely to report certain health problems than men with choroideremia who still had functional vision such as:
· high blood pressure,
· high cholesterol, or
· diabetes
One possible interpretation of this finding is that these conditions might contribute to increasing the severity or speed of onset of vision loss in choroideremia. Anecdotal reports have suggested that statins, drugs commonly used to treat high cholesterol, may affect vision adversely in men with choroideremia, and this survey also revealed that men taking statins were more likely to have severe vision loss.
This survey highlights some important health concerns for people with choroideremia which may shape future research and ultimately lead to improvements in clinical care for both affected men and female carriers.
ARVO Presentation
A Web-based Health Survey of Choroideremia Patients. Presented Wednesday May 4, 2011.Qi Zhou, Shelly Benjaminy, Ian M. MacDonald. University of Alberta, Edmonton.