Hyunjoo Jean Lee

The epigenome is defined by DNA methylation patterns and the associated posttranslational modifications of histones. This histone code determines the expression status of individual genes dependent upon their localization on the chromatin. The silencing of gene expression is associated with deacetylated histones, which are often found to be associated with regions of DNA methylation as well as methylation at the lysine 4 residue of histone 3. In contrast, the activation of gene expression is associated with acetylated histones and methylation at the lysine 9 residue of histone 3. The histone deactylases play a major role in keeping the balance between the acetylated and deacetylated states of chromatin. Histone deacetylases (HDACs) are divided into three classes: class I HDACs (HDACs 1, 2, 3, and 8) are similar to the yeast RPD3 protein and localize to the nucleus; class II HDACs (HDACs 4, 5, 6, 7, 9, and 10) are homologous to the yeast HDA1 protein and are found in both the nucleus and cytoplasm; and class III HDACs form a structurally distinct class of NAD-dependent enzymes that are similar to the yeast SIR2 proteins. Since inappropriate silencing of critical genes can result in one or both hits of tumor suppressor gene (TSG) inactivation in cancer, theoretically the reactivation of affected TSGs could have an enormous therapeutic value in preventing and treating cancer. Indeed, several HDAC inhibitors are currently being developed and tested for their potency in cancer chemotherapy. Importantly, these agents are also potentially applicable to chemoprevention if their toxicity can be minimized. Despite the toxic side effects and lack of specificity of some of the inhibitors, progress is being made. With the elucidation of the structures, functions and modes of action of HDACs, finding agents that may be targeted to specific HDACs and potentially reactivate expression of only a defined set of affected genes in cancer will be more attainable.

Aniridia classically presents with a bilateral congenital absence or malformation of the irides, foveal hypoplasia, and nystagmus, and patients tend to develop visually significant pre-senile cataracts and keratopathy. Additionally, they are at high risk for developing glaucoma. Classic aniridia can be genetically defined as the presence of a PAX6 gene deletion or loss-of-function mutation that results in haploinsufficiency. Variants of aniridia, which include a condition previously referred to as autosomal dominant keratitis, are likely due to PAX6 mutations that lead to partial loss of PAX6 function. Aniridia-associated keratopathy (AAK) is a progressive and potentially debilitating problem affecting aniridic patients. The current treatments for AAK are to replace the limbal stem cells through keratolimbal allograft (KLAL) with or without subsequent keratoplasty for visual rehabilitation, or to implant a Boston type 1 keratoprosthesis. Future therapies for AAK may be aimed at the genetic modification of corneal limbal stem cells.

Importance: Several ophthalmic diseases disproportionately affect racial and ethnic minority patients, yet most clinical trials struggle to enroll cohorts that are demographically representative of disease burden; some barriers to recruitment include time and transportation, language and cultural differences, and fear and mistrust of research due to historical abuses. Incorporating diversity within the research team has been proposed as a method to increase trust and improve engagement among potential study participants. Objective: To examine how demographic factors of potential research participants and personnel may be associated with patient consent rates to participate in prospective ophthalmic clinical studies. Design, Setting, and Participants: This retrospective cohort study included patients from an urban, academic hospital who were approached for consent to participate in prospective ophthalmic clinical studies conducted between January 2015 and December 2021. Main Outcomes and Measures: Multivariable logistic regression assessing associations between patient and research personnel demographics and rates of affirmative consent to participate was used. Results: In total, 1380 patients (mean [SD] age, 58.6 [14.9] years; 50.3% male) who were approached for consent to participate in 10 prospective ophthalmic clinical studies were included. Of prospective patients, 566 (43.5%) were Black; 327 (25.1%), Hispanic or Latino; 373 (28.6%), White; 36 (2.8%), other race and ethnicity; and 78 (5.8%) declined to answer. Black patients (odds ratio [OR], 0.32; 95% CI, 0.24-0.44; P < .001) and Hispanic or Latino patients (OR, 0.31; 95% CI, 0.20-0.47; P < .001) were less likely to consent compared with White patients. Patients with lower socioeconomic status were less likely to consent than patients with higher socioeconomic status (OR, 0.43; 95% CI, 0.33-0.53; P < .001). Concordance between patient and research staff race and ethnicity was associated with increased odds of affirmative consent (OR, 2.72; 95% CI, 1.99-3.73; P < .001). Conclusions and Relevance: In this cohort study, patients from underrepresented racial and ethnic groups and those with lower socioeconomic status were less likely to participate in ophthalmic clinical studies. Concordance of race and ethnicity between patients and research staff was associated with improved participant enrollment. These findings underscore the importance of increasing diversity in clinical research teams to improve racial and ethnic representation in clinical studies.

Keratoconus is a disease of the cornea that results in progressive steepening and thinning of the cornea and subsequent vision loss. It nearly always presents as a bilateral disease, suggesting that there is an underlying abnormality of the corneas that becomes manifest with time. However, the mechanisms underlying the development of keratoconus are largely unknown. Associations reported between keratoconus and systemic diseases are abundant in the literature, and the list of possible associations is very long. We found that atopy, Down syndrome, and various connective tissue diseases were the most frequently cited associations in our broad literature search. Additionally, Diabetes Mellitus has been increasingly studied as a possible protective factor against keratoconus. In this review, we have summarized the evidence for and against these particular systemic conditions and keratoconus and have discussed some of the implications of keratoconus patients having these conditions.