Strabismus genetics across a spectrum of eye misalignment disorders

Abstract

Eye misalignment, called strabismus, is amongst the most common phenotypes observed, occurring in up to 5% of individuals in a studied population. While misalignment is frequently observed in rare complex syndromes, the majority of strabismus cases are non-syndromic. Over the past decade, genes and pathways associated with syndromic forms of strabismus have emerged, but the genes contributing to non-syndromic strabismus remain elusive. Genetic testing for strabismus risk may allow for earlier diagnosis and treatment, as well as decreased frequency of surgery. We review human and model organism literature describing non-syndromic strabismus, including family, twin, linkage, and gene expression studies. Recent advances in the genetics of Duane retraction syndrome are considered, as relatives of those impacted show elevated familial rates of non-syndromic strabismus. As whole genome sequencing efforts are advancing for the discovery of the elusive strabismus genes, this overview is intended to support the interpretation of the new findings.

Altered Protein Composition and Gene Expression in Strabismic Human Extraocular Muscles and Tendons

“…1 Both genetic and environmental factors contribute to strabismus, 2–4 but in contrast to the rare forms of congenital strabismus, 5 the genetics and molecular mechanisms of common strabismus are not well understood. 6 The etiology of strabismus involves multiple components of the oculomotor system, from the extraocular muscles (EOMs) to visual cortex. 6,7 …”

“…6 The etiology of strabismus involves multiple components of the oculomotor system, from the extraocular muscles (EOMs) to visual cortex. 6,7 …”

Comparison of Visual Acuity for Different Amount of Deviation of Alternate Exotropia

“…That's why; at the temporal region cone cell density is reduced compared to foveal region. So, in case of Alternate Exodeviation, deterioration of visual acuity is being observed [4][5][6][7].…”

Comparison of Contrast Sensitivity for Different Amount of Deviation of Alternate Esotropia

“…With increase in ocular deviation, contrast sensitivity is simultaneously deteriorated. So, in cases of Alternate deviation like Eso deviation, alternately images are focused at the nasal para foveal region and deteriorate the contrast sensitivity [4][5][6][7].…”