Search for recessive retinitis pigmentosa genes using RNA expression analysis in lymphoblasts

Recessive retinitis pigmentosa (RP) is often caused by nonsense mutations that lead to low mRNA levels as a result of nonsense-mediated decay. Some RP genes are expressed at detectable levels in leukocytes as well as in the retina. We designed a microarray-based method to find recessive RP genes based on low lymphoblast mRNA expression levels Keywords: Recessive mutations; mRNA expression; nonsense mediated-decay; retinitis pigmentosa; lymphocyte; Affymetrix genechip Human Genome U133Plus2.0. We established lymphoblast cell lines from 13 unrelated index patients with recessive RP as well all of their affected siblings (1 sibship with 4 affected members, 5 with 2 affected members, and 7 isolates) and 4 controls. RNA was isolated and hybridized on Affymetrix genechip Human Genome U133Plus2.0. After normalization, expression levels of the individual families were compared to the other samples; significance was tested using the Student t-test. The most significant suitable candidate genes were sequenced to screen for disease causing mutations and/or analyzed for segregation in the family.