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Kari Branham, Jillian Huang, Kanishka Jayasundera, John Heckenlively; Inheritance of Retinitis Pigmentosa: Update in the Era of Genetic Testing. Invest. Ophthalmol. Vis. Sci. 2013;54(15):4019.
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© ARVO (1962-2015); The Authors (2016-present)
To determine how often inheritance of RP varied between information gathered from pedigree analysis and results of genetic testing.
Pedigrees from 104 probands with RP who had positive and informative genetic test results were reviewed. The analysis of the pedigree included the number of individuals affected, gender, familial relationships, and (when available) age of onset of RP. Pedigrees were classified as AD if there were two or more generations of affected individuals and there was male to male transmission or affected males and females with similar disease severity/age of onset. Pedigrees were considered AR pedigrees if there was a single generation of more than one person affected (males and females or females only) or if there was parental consanguinity. Pedigrees were considered XL if there was no evidence of male to male transmission and only males affected or males affected severely and females affected mildly or at a later age of onset. Pedigrees not fitting into one of those categories were descriptively described as male siblings only affected or isolate cases. Genetic testing results were also recorded.
Among the 37 AD families, five families were determined to be XL through genetic testing. In the eight AR families tested, one family had an AD mutation. In the 38 XL pedigrees, two had mutations in AD genes and 36 in XL. In the 17 isolated cases tested, six had mutations in AR genes and 11 in XL genes. Finally, in the four families with male siblings affected, all had mutations in XL genes. In summary, 8/83 (9.6%) of patients had a different inheritance for their RP based on genetic testing than what was suggested based on pedigree analysis alone. Moreover, the inheritance could be clarified for an additional 21 families where there were isolated cases or only male siblings affected in which inheritance was ambiguous based on pedigree analysis alone.
While pedigree analysis is an essential aspect of providing care to patients with inherited retinal dystrophies, successful genetic testing provides the ability to perform more precise genetic counseling to patients.
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