Washington: A new study has claimed to have found the link between patient's urine to gene mutations that cause retinitis pigmentosa, or RP, an inherited, degenerative disease that results in severe vision impairment and often blindness.
Ziqiang Guan, an associate research professor of biochemistry in the Duke University Medical School and a contributing author of the study, and his collaborators had previously sequenced the genome of this family and found that the children with RP carry 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, containing 19 isoprene units, 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 the Ashkenazi Jewish origin, and 1 in 322 Ashkenazi carries one copy of the mutation.
Guan said that he knew from his previous experience in analyzing urine samples from liver disease patients that I can readily detect dolichols by liquid chromatography and mass spectrometry.
Using these techniques, he 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 DHDDS mutation from that caused by other mutations.
The study has been published online in the Journal of Lipid Research.