New Animal Model Improves Understanding of XLRP Due to RP2 Mutations

June 12, 2013

Foundation-funded researchers have created a mouse model of X-linked retinitis pigmentosa (XLRP) caused by defects in the gene RP2 — an advancement that gives them a platform for learning more about the disease and developing potential therapies for future human studies. Results of the research were published in the journal Investigative Ophthalmology & Visual Science (IOVS).

The investigators determined that the movement of opsins — proteins necessary for the processing of light that makes vision possible — was compromised predominantly in the cones of the RP2-deficient mice. Cones are the photoreceptors that provide central and color vision and the ability to perceive details.

The researchers noted that the findings for RP2-deficient mice were consistent with their study of RP-2-associated XLRP in humans. “In a large clinical analysis, we showed that a majority of RP2 patients exhibit early-onset macular atrophy and cone dysfunction,” says Dr. Hemant Khanna, the study’s lead investigator from the University of Massachusetts Medical School.

“Although rods exhibit dysfunction at an early stage, the progression of rod dysfunction and degeneration is less severe.”

RP2 is one of three genes linked to XLRP, accounting for about 15 percent of cases. Defects in RPGR are associated with 75 percent of cases. The gene OFD1 was recently linked to XLRP, but is believed to be a relatively rare cause of the condition.

XLRP primarily affects males. Women are usually unaffected carriers of the disease, but can sometimes experience significant vision loss as well.

Other researchers participating in the study were: Drs. Linjing Li, University of Massachusetts Medical School; Naheed Khan, University of Michigan; Tody Hurd, University of Edinburgh; Amiya Kumar Ghosh, University of Michigan; Christina Cheng, University of British Columbia; Robert Molday, University of British Columbia; John R. Heckenlively, University of Michigan; and Anand Swaroop, National Eye Institute, National Institutes of Health.