IFT88 mutations identified in individuals with non-syndromic recessive retinal degeneration result in abnormal ciliogenesis
Whole genome sequencing (WGS) was performed to identify the variants responsible for inherited retinal degeneration (IRD) in a Caucasian family. Segregation analysis of selected rare variants with pathogenic potential identified a set of compound heterozygous changes p.Arg266*:c.796C>T and p.Ala568Thr:c.1702G>A in the intraflagellar transport protein-88 (IFT88) gene segregating with IRD. Expression of IFT88 with the p.Arg266* and p.Ala568Thr mutations in mIMDC3 cells by transient transfection and in HeLa cells by introducing the mutations using CRISPR-cas9 system suggested that both mutations result in the formation of abnormal ciliary structures. The introduction of the IFT88 p.Arg266* variant in the homozygous state in HeLa cells by CRISPR-Cas9 genome-editing revealed that the mutant transcript undergoes nonsense-mediated decay leading to a significant depletion of IFT88 transcript. Additionally, abnormal ciliogenesis was observed in these cells. These observations suggest that the rare and unique combination of IFT88 alleles observed in this study provide insight into the physiological role of IFT88 in humans and the likely mechanism underlying retinal pathology in the pedigree with IRD.
We are grateful to Dr. Frans PM Cremers, Department of Human Genetics, Radboud University Nijmegen Medical Center, for screening his collection of IRD patients for mutations in the IFT88 gene.
The Foundation Fighting Blindness, Research to Prevent Blindness, NIH-EY21237, P30-EY22589. Shyamanga Borooah was funded by a Fulbright-Fight For Sight Scholarship and Global Ophthalmology Awards Program Fellowship award.
Compliance with ethical standards
Conflict of interest
Authors declare that there is no conflict of interest.
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