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Comparative Natural History of Visual Function From Patients With Biallelic Variants in BBS1 and BBS10
Monika K Grudzinska Pechhacker1,2, Samuel G Jacobson3, Arlene V Drack4
1Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, Canada.
Investigative Ophthalmology & Visual Science
|December 23, 2021
Summary
Bardet-Biedl syndrome (BBS) patients with BBS10 gene variants experience earlier and more severe retinal degeneration than those with BBS1 variants. Visual function decline is also more rapid in BBS10 cases, highlighting genetic subtype differences in BBS progression.
Area of Science:
- Ophthalmology
- Genetics
- Medical Research
Background:
- Bardet-Biedl syndrome (BBS) is a rare genetic disorder characterized by a wide range of symptoms, including retinal degeneration.
- Biallelic variants in Bardet-Biedl syndrome genes, such as BBS1 and BBS10, are known causes of BBS-related retinal dystrophy.
- Understanding the natural history of visual function decline in different BBS genetic subtypes is crucial for patient management and therapeutic development.
Purpose of the Study:
- To compare the progression of visual function in patients with retinal degeneration caused by biallelic variants in BBS1 versus BBS10 genes.
- To investigate the relationship between specific genetic subtypes of BBS and the rate of visual function loss.
Main Methods:
- Retrospective analysis of data from 67 individuals with biallelic variants in BBS1 (n=38) or BBS10 (n=29) recruited from nine international academic centers.
- Collected data included genotypes, age of onset, best corrected visual acuity (VA), refractive error, fundus imaging, optical coherence tomography (OCT), kinetic visual field perimetry (VF), electroretinography (ERG), and systemic phenotype.
- Comparison of visual function measures (VA, VF, ERG) and disease progression between BBS1 and BBS10 cohorts.
Main Results:
- Patients with BBS10 variants showed earlier onset and more severe retinal degeneration compared to those with BBS1 variants.
- Electroretinography (ERG) results became undetectable earlier in the BBS10 cohort.
- Visual acuity (VA) and visual field (VF) declined more rapidly in patients with BBS10 compared to BBS1 variants.
- Rod-cone dystrophy (RCD) was prevalent in both groups, with cone-rod dystrophy (CORD) and cone dystrophy (COD) observed in specific subgroups.
Conclusions:
- Retinal degeneration progresses more rapidly and severely in Bardet-Biedl syndrome patients with BBS10 variants than in those with BBS1 variants.
- The natural history and rate of visual function change in BBS are influenced by the specific genetic subtype (BBS1 vs. BBS10).
