CRB1 mutations may result in retinitis pigmentosa without para-arteriolar RPE preservation.

Purpose: To report a new phenotype in retinitis pigmentosa (RP) patients with CRB1 mutations at the RP12 locus.
Patients: Thirty-seven patients from two Pakistani families with severe retinitis pigmentosa.
Methods: Samples were screened with single-strand conformation polymorphism analysis followed by DNA sequencing of the coding sequence of the CRB1 gene.
Results: Two novel CRB1 mutations were discovered. No patients had evidence of preservation of the para-arteriolar retinal pigment epithelium (PPRPE) that has been previously reported in all cases of RP associated with CRB1 mutations.
Conclusions: Patients with severe autosomal recessive (or simplex) RP who lack the finding of PPRPE should not be excluded from molecular analysis of CRB1 purely because they lack the clinical feature of PPRPE. This report illustrates that RP at the RP12 locus is not clinically uniform. The absence of PPRPE cannot be used to exclude CRB1 as a potential molecular explanation for RP.