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New Urine Test Could Diagnose Eye Disease

Researchers Find Gene Mutation Linked to Retinitis Pigmentosa (October 8)

A new study from Duke University says it can link what is in a patient’s urine to gene mutations that cause retinitis pigmentosa (RP), an inherited, degenerative disease that results in severe vision impairment and often blindness. The findings appear online in the Journal of Lipid Research.

The researchers had previously sequenced the genome of a family in which three of four siblings had RP. They found that the children with RP carried two copies of a mutation at the dehydrodolichol diphosphate synthase (DHDDS) gene, which makes the enzyme that synthesizes organic compounds called dolichols. In humans, dolichol-19 is the most abundant species.

The DHDDS mutation, which was found in 2011, is the latest addition to more than 60 gene mutations that have been implicated in RP. This mutation appears to be prevalent in RP patients of Ashkenazi Jewish origin.

Using mass spectrometry techniques, Dr. Rong Wen analyzed urine and blood samples from the six family members and found that instead of dolichol-19, the profiles from the three siblings with RP showed dolichol-18 as the dominant species. The parents, who each carry one copy of the mutated DHDDS gene, showed intermediate levels of dolichol-19 and higher levels of dolichol-18 than their healthy child. Guan believes dolichol profiling could effectively distinguish RP caused by the DHDDS mutation from that caused by other mutations.

Guan and his colleagues hope to develop the dolichol profiling method as a first-line diagnostic test to identify RP patients with abnormal dolichol metabolism. They think this mass spectrometry-based detection method will help physicians provide more personalized care to RP patients, especially to young children whose retinal degeneration has not fully developed.

There are currently no treatments for RP, but Guan hopes his research will shed light on potential drug design strategies for treating RP caused by DHDDS mutation.

[Source: Duke University, October 8, 2013.]

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