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Saturday, 23 March 2013

Cause of Stargardt blindness disproved



Research by vision scientists in America has disproved the previous belief that a lack of very long chain fatty acids in photoreceptor cells caused blindness in children with Stargardt type 3 retinal degeneration. 
 
Researchers at the University of Utah’s John A. Moran Eye Center bred mice that lacked fatty acids in their photoreceptor cells and found that the eyesight of the mice was ‘normal.’
 
The cause for blindness in children with the incurable eye disease is now unknown. 
 
Leading researchers, David Krizaj, an associate professor of ophthalmology and visual sciences at the Moran Eye Center, stated: “There was no defect in their daytime or night time vision. The lack of very long chain fatty acids does not appear to compromise vision in itself.”
 
Type 3 Stargardt disease is a rare dominant form which is caused by a mutation in ELOVL4, a gene that encodes an enzyme which helps to make fatty acids gained through diet into forms which can be incorporated into cell membranes. In the past proving that the lack of fatty acids caused blindness has been difficult as mice which has ELOVL4 removed would not survive. Researchers overcame this problem by only engineering mice which only lacked the gene in their photoreceptor. 
 
Stargardt disease affects around one in 10,000 children between the ages of six and 20. While there is no treatment, evidence suggests that nutritional supplements and protecting the eyes from UV could slow the progression of blindness. 
 
“If it’s not the loss of fatty acids causing the disease, then we’ll have to find other strategies to help these kids,” professor Krizaj added.
 
The research was published in PNAS online