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• Interesting study
• Posted: 2008-04-15 20:07:02 By Carol C
• I just read a report on the web( 2008, so very recent publication)of a set of fraternal twin males ( 2 different eggs, as closely related as any siblings)both inheriting their RPGR mutation from the mother. But one had X-linked cone-rod dystrophy ( cones effected more than rods, visual acuity, color vision problems early with night vision only effected late in course), and the other had typical XLRP, starting with loss of night vision and loss of peripheral vision. They have long known that the same mutation can take a different course, some in the same family losing vision sooner than others, but this seems quite different. It might explain why my brother has all the classic symptoms of XLCRD, legally blind at age 34, doesn't drive at all, while a 4th cousin with same exact mutation (DNA test) has typical RP symptoms: no night viaion, peripheral vision issues, but still driving during the day at age 44, central vision clear. Why would the exact same amino acid "mistake" effect the cones primarily in one person, and the rods in another? I guess they suspect another genetic compnent, but if they have to search the whole set of chromosomes for it, it doesn't seem likely we'll know any time soon. Carol