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The retinal degeneration(rd) mouse is a commonly-studied animal model of the family of human-inherited retinal blindness known as retinitis pigmentosa, and is a likely model in which therapies for these conditions will continue to be developed and tested. Mutation of the beta-subunit of the rod photoreceptor cell-specific cyclic GMP phosphodiesterase is known to cause photoreceptor apoptosis in these mice. However, the molecular phenotype of this mutation in terms of quantitative levels of the phosphodiesterase alpha- and beta-subunit messenger RNAs remains unknown. In this study, the expression of the alpha- and beta-phosphodiesterase subunits is compared in C57BL/6J +/+, rd /+, and rd / rd mouse retinas. Using the techniques of quantitative reverse transcription polymerase chain reaction and quantitative in situ hybridization, the expression of the subunit mRNAs was measured in retinas of postnatal mice 0-14 days of age. Additionally, full length coding sequences were amplified for both subunits, and the beta-phosphodiesterase subunit mRNA was further evaluated for evidence of alternative splicing. Lastly, a relative decrease in expression of the mutant beta-phosphodiesterase allele in rd /+ mice was observed., (Copyright 2000 Academic Press.)

The family of inherited ocular diseases that is collectively known as retinitis pigmentosa is a major cause of progressive retinal disease worldwide. As such, this family of diseases has been the object of much scientific scrutiny, both clinical and basic. The recent application of molecular genetic analyses has heralded the rapid elucidation of the underlying gene defects in many cases. In this article, the fundamental clinical and electroretinographic characteristics of retinitis pigmentosa will be recalled. Additionally, the current understanding of the genetic causes of retinitis pigmentosa will be reviewed, and the identified causative genes will be classified into groups related by function.

Deletion mutations and linkage mapping have localized an X-linked retinitis pigmentosa locus to Xp21, and a disease gene (RPGR) has been characterized. However, mutations have not been identified in most families expected to segregate the disease at this locus. Here, a retina-specific mRNA transcript from the Duchenne muscular dystrophy gene is identified. Based on these data, it is hypothesized that the Duchenne muscular dystrophy gene may represent a second Xp21 site at which retinitis pigmentosa mutations occur., (Copyright 2000 Academic Press.)