Neuro-ophthalmic disorders resulting from defects in the gamma tubulin ring complex: a clinically oriented review

The gamma-tubulin ring complex (γ-TuRC) is a highly conserved and ubiquitously expressed complex necessary for proper microtubule nucleation and mitotic spindle function. While it is well established that the microtubule network plays a critical role in proper neurodevelopment, the clinical phenotypes associated with defects in the γ-TuRC have only been characterized recently. Generally, the neurologic features associated with γ-TuRC defects include microcephaly associated with chorioretinopathy (MCCRP), lissencephaly, cerebellar atrophy, motor and speech delay, and intellectual disability with variable severity. Prominent ocular features including microphthalmia, nystagmus, and abnormal retinal vasculature or vitreoretinopathy have been characterized in MCCRP related to defects specifically in two γ-TuRC proteins, TUBGCP4 and TUBGCP6. The purpose of this study is to provide a clinically oriented review of the γ-TuRC and the neuro-ophthalmic developmental disorders resulting from defects in this complex. At this time, it is unknown why affected patients only demonstrate neurologic and ophthalmic phenotypes despite the ubiquitous expression of this critical protein complex; this represents an important unmet clinical and basic research need. Ophthalmic genetics and pediatric ophthalmology specialists should be familiar with γ-TuRC-related disorders, particularly because of the need for multi-disciplinary care for these patients and the phenotypic similarities to other inherited retinal conditions.