Ocular Phenotype of Peters-Plus Syndrome

Characterization of Cell Surface Glycan Profiles in Human and Mouse Corneas Using Lectin Microarrays

The advent of high-throughput sequencing technologies has facilitated the profiling of glycosylation genes at a single-cell level in complex biological systems, but the significance of these gene signatures to the composition of the glycocalyx remains ambiguous. Here, we used lectin microarrays to characterize the composition of cell surface glycans in human and mouse corneas and determine its relationship to single-cell transcriptomic data. Our results identify a series of cell surface glycan signatures that are unique to the different cell types of the human cornea and that correlate, to a certain extent, with the transcriptional expression of glycosylation genes. These include pathways involved in the biosynthesis of O-glycans in epithelial cells and core fucose on stromal and endothelial cell surfaces. Moreover, we show that human and mouse corneas display some structural differences in terms of cell surface glycan composition. These results could provide insights into the specialized function of individual cell types in the cornea and foster the identification of novel cornea-specific biomarkers.

Congenital Corneal Opacity in 22q11.2 Deletion Syndrome: A Case Series

PURPOSE

The purpose of this study was to describe the deep phenotype of congenital corneal opacities (CCO) in patients with 22q11.2 deletion syndrome (22q11.2 DS) and to identify putative regions or genes that could explain the CCO.

METHODS

A retrospective chart review was conducted to identify patients with 22q11.2 DS seen in the ophthalmology clinic of a tertiary referral children's hospital. Thirty patients were identified, with molecular confirmation. Twenty-six did not show structural anterior segment anomalies aside from posterior embryotoxon (n = 4), whereas 4 had bilateral CCO, of which 3 had preoperative images. We reviewed medical, operative, and pathology reports; anterior segment optical coherence tomography; high-frequency ultrasound; histopathologic slides; and genetic testing. To identify putative genes responsible for CCO, chromosomal breakpoints in patients with and without CCO were compared.

RESULTS

In the 3 patients with preoperative imaging and CCO, a pattern of paracentral corneal opacification with central clearing accompanied by iridocorneal or keratolenticular adhesions was observed. Anterior segment optical coherence tomography and histopathologic images showed central stromal thinning with a residual structure consistent with Descemet membrane. One patient presented at birth with unilateral corneal perforation, suggestive of likely stromal thinning. A comparison of the breakpoints across all cases failed to reveal unique regions or genes in patients with CCO.

CONCLUSIONS

22q11.2 DS can rarely be associated with CCO. We describe a consistent pattern of central clearing related to posterior stromal thinning, with or without ICA/KLA. Possible candidate genes for corneal opacification in 22q11.2 DS remain elusive.

Peter's anomaly-A homeotic gene disorder

Peter's anomaly is a rare form of congenital anterior segment dysgenesis of the eye. Varying degrees of central corneal opacity and lenticulo-corneal or irido-corneal synechiae are the key hallmarks. The association of Peter's anomaly along with short stature, rhizomelia, broad short hands or brachydactyly, with facial dysmorphism, cleft lip, cleft palate, genitourinary and cardiovascular anomalies is a distinct and is often termed Peter's plus syndrome. Early detection is imperative to prevent sensory deprivation amblyopia. Glaucoma can be present at initial diagnosis or at any stage later, but treatment can be difficult. For the dense leukoma, corneal graft may be needed but visual prognosis is poor. Research focussing on gene editing and regenerative medicine using native corneal endothelial cells is ongoing.