IFT81 as a Candidate Gene for Nonsyndromic Retinal Degeneration.

Area of Science:

• Genetics and Molecular Biology
• Ophthalmology
• Cell Biology

Background:

• Intraflagellar transport (IFT) is crucial for ciliary function, essential for photoreceptor maintenance.
• IFT-B complex proteins are vital for bidirectional ciliary transport.
• While linked to syndromic ciliopathies, IFT-B proteins haven't been associated with nonsyndromic retinal dystrophies.

Purpose of the Study:

• To investigate the role of intraflagellar transport (IFT) mutations in nonsyndromic retinal dystrophies.
• To explore the impact of IFT81, a core IFT-B component, in the context of these conditions.

Main Methods:

• Whole exome sequencing in 50 patients with cone-rod dystrophy (CRD) previously screened for known retinal disease genes.
• In vitro cell system analysis to assess the pathogenicity of candidate mutations.
• In vivo zebrafish assays to further validate the functional impact of identified variants.

Main Results:

• Compound heterozygous mutations in IFT81 were identified in a patient with nonsyndromic CRD.
• Functional analyses in cell culture and zebrafish models demonstrated the pathogenic nature of an IFT81 missense variant.
• Loss of IFT81 function impairs ciliogenesis, with the identified missense variant showing significantly reduced rescue capabilities.

Conclusions:

• Mutations in IFT81, a core IFT-B protein, are associated with nonsyndromic cone-rod dystrophy.
• This study represents the first report linking IFT81 mutations to nonsyndromic retinal dystrophy.
• The findings expand the phenotypic spectrum of IFT-B complex component-related disorders.