As part of our project to generate a catalogue of genes with potential relevance to human retinal disease, we have cloned a transcript abundantly expressed in the human retina and testis. Analysis of the deduced 1322 amino acid protein sequence demonstrates that it encodes a novel WD repeat protein, termed WDR17. The N-terminal moiety of the WDR17 protein is predicted to consist of at least 12 conserved WD repeats that likely adopts a beta-propeller-like structure. Homology searches with the C-terminal region revealed no similarity to known or hypothetical proteins. However, putative orthologous ESTs with 82-91% identity to the human cDNA were found in several mammalian species including rodents, pig and cattle, suggesting that WDR17 represents an evolutionarily novel subtype of WD repeat proteins with unique function(s) in higher eukaryotes. Temporal expression analysis in the murine eye showed that transcription of WDR17 begins prenatally, suggesting a functional role of the protein in the early stages of retinal development. Human WDR17 maps to the same chromosomal interval as the locus for autosomal recessive retinitis pigmentosa (RP29) on 4q34, making it a candidate for this disease gene. Sequencing of the entire coding region of WDR17 in an affected patient of the original RP29 pedigree has not revealed any disease-causing sequence variations likely excluding WDR17 as the gene underlying RP29.