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Urine Test Helps Diagnose RP Caused by DHDDS Mutations

Microscope and lab equipmentResearchers from the Bascom Palmer Eye Institute of the University of Miami and Duke University are developing a urine test to help determine if the cause of autosomal recessive retinitis pigmentosa (arRP) in Ashkenazi Jews is mutations in the gene DHDDS. While it isn’t a substitute for a diagnosis through genetic testing, the urine test can verify that a given DHDDS mutation is, in fact, causing RP. (Some mutations might be benign.) It can also be used to identify people who are unaffected carriers of DHDDS-associated arRP. Results of the researchers’ related investigation were published in the Journal of Lipid Research.

Keep in mind that several other genes have been linked to retinal degenerations in Ashkenazi Jews, including those in which mutations can cause RP, Usher syndrome and Leber congenital amaurosis. Also, a genetic test — screening a person’s DNA — remains the best method for diagnosing these conditions. If you have any questions about genetic testing, it is best to consult a genetic counselor.

A benefit of the urine test is that it can tell us more about the effect of a DHDDS mutation. The test works by measuring ratios of two lipids. In people with DHDDS mutations — both those with arRP and unaffected carriers — the ratio is different than in those without mutations.

The test might also be helpful in determining the effect of a systemic DHDDS therapy, which would likely bring the lipid ratio to normal throughout the body. However, it would not work for evaluating treatments that were delivered only to the eye (e.g., a gene therapy).

The DHDDS urine test is still only being used in a research setting. The investigators plan to expand its clinical use in the future.

In 2011, Bascom Palmer researchers identified DHDDS mutations as a cause of arRP in Ashkenazi Jews. About 12 percent of arRP in this population is caused by DHDDS mutations.  Bascom Palmer scientists have created a mouse model of the condition, and are developing gene and neuroprotective therapies to treat it.

Developers of the DHDDS urine test are Byron Lam, M.D., and Rong Wen, M.D., Ph.D., at Bascom Palmer, and Ziqiang Guan, Ph.D., at Duke.

We’ll be sure to report on additional advancements in DHDDS research as we learn about them.

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3 Responses to 'Urine Test Helps Diagnose RP Caused by DHDDS Mutations'

  1. Tiffany Leitz says:

    Oh my goodness! I live in ft. Lauderdale and I have seen dr. Lam for an eye exam after I found out I had arRP but it was prior to me finding out through genetic testing in Iowa by dr. Edwin Stone that my mutated RP causal gene is DHDDS GENE! I’m desperate for help as my condition has gotten pretty bad and would be HAPPY to give a urine sample for dr. Lam to test it if it could help him?!!?? And hopefully help me too maybe!! I never called to tell him the gene and I should have but this is AMAZING to read as I keep hearing people say they have not heard of the DHDDS gene being a causal mutated RP gene in Ashkanazi Jews! And what’s really crazy is I just left a message for dr.lams secretary Nancy last week and today!! Please, please get back to me!! I’m desperate for help and I’m willing to do anything for help!! Not to mention dr. Lam has been the only scientist who my mom and I felt was just an absolute genius once leaving my appointment with him a couple years back!! I look forward to your reply! I do have my ERG records from mass eye and ear along with my genetic testing result records from dr. Stone if dr. Lam would like to see them! Thank you!!!

  2. Marilyn says:

    Wow! After all I got a weblog from where I be able to truly obtain useful data
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