Analyzing pre-symptomatic tissue to gain insights into the molecular and mechanistic origins of late-onset degenerative trinucleotide repeat disease.

How genetic defects trigger the molecular changes that cause late-onset disease is important for understanding disease progression and therapeutic development. Fuchs' endothelial corneal dystrophy (FECD) is an RNA-mediated disease caused by a trinucleotide CTG expansion in an intron within the TCF4 gene. The mutant intronic CUG RNA is present at one-two copies per cell, posing a challenge to understand how a rare RNA can cause disease. Late-onset FECD is a uniquely advantageous model for studying how RNA triggers disease because: (i) Affected tissue is routinely removed during surgery; (ii) The expanded CTG mutation is one of the most prevalent disease-causing mutations, making it possible to obtain pre-symptomatic tissue from eye bank donors to probe how gene expression changes precede disease; and (iii) The affected tissue is a homogeneous single cell monolayer, facilitating accurate transcriptome analysis. Here, we use RNA sequencing (RNAseq) to compare tissue from individuals who are pre-symptomatic (Pre_S) to tissue from patients with late stage FECD (FECD_REP). The abundance of mutant repeat intronic RNA in Pre_S and FECD_REP tissue is elevated due to increased half-life in a corneal cells. In Pre_S tissue, changes in splicing and extracellular matrix gene expression foreshadow the changes observed in advanced disease and predict the activation of the fibrosis pathway and immune system seen in late-stage patients. The absolute magnitude of splicing changes is similar in pre-symptomatic and late stage tissue. Our data identify gene candidates for early drivers of disease and biomarkers that may represent diagnostic and therapeutic targets for FECD. We conclude that changes in alternative splicing and gene expression are observable decades prior to the diagnosis of late-onset trinucleotide repeat disease.

Early onset endophthalmitis caused by Aspergillus species following cataract surgery.

PURPOSE: To report a series of patients with early onset Aspergillus endophthalmitis following cataract surgery. DESIGN: Retrospective consecutive case series. METHODS: Medical records were reviewed of all cases of endophthalmitis caused by Aspergillus after cataract surgery treated at the authors' practices between 1992 and 2005. RESULTS: Five patients were identified. Two patients were immunocompromised (one on oral corticosteroids and one on chemotherapy for lung cancer). The mean number of days between cataract surgery and diagnosis with endophthalmitis was 29 (range, 10 to 62 days). Three eyes (60%) were enucleated despite a variety of treatments. In addition to vitrectomy and injection of antifungal agents, the other two eyes underwent surgical debridement of a localized necrotic nidus. Final visual acuity was 20/30 in one eye and 20/200 in the remaining eye. CONCLUSIONS: Aspergillus should be considered in the differential diagnosis of early onset endophthalmitis following cataract surgery. Visual outcomes are generally poor and enucleation is common in these patients.