Northern hybridization analysis of UROS poly(A)⁺ RNA isolated from lymphoblasts of unrelated CEP patients. A single 1.5-kb transcript was observed for the normal person (Nl) and the CEP patients, with the exception of patients 3 and 6 who had longer transcripts of 1.6, 1.8, and 2.0 kb, suggesting that their CEP mutation(s) altered UROS pre-mRNA splicing.