Abstract
Purpose:
To describe a family with nonsyndromic retinitis pigmentosa (RP) due to BBS2 mutations.
Methods:
The proband was evaluated in retinal dystrophy clinic. Family and medical histories were reviewed. Fundus photographs, visual fields, and OCT were obtained. Molecular analysis via Next Generation Sequencing (NGS) found BBS2 variants, which were confirmed by Sanger Sequencing. Segregation analysis of the variants was performed among available family members. In silico analysis of the identified missense change was evaluated using the Polyphen-2, pMut, and SIFT algorithms.
Results:
A 41 year-old Caucasian female presented with a diagnosis of RP. Eye exam showed significant visual field constriction, nyctalopia, and peripheral pigmentary changes. Family history at the time was non-contributory. Her brother, age 39, had no visual complaints, and both of her parents were asymptomatic. DNA analysis for the recessive RP panel was negative. Later analysis via NGS of the RetNet genes found 2 variants in the BBS2 gene. R275X is known to be pathogenic and P134R is a novel mutation. Co-segregation analysis determined that the variants were inherited independently from each parent. The proband’s brother also carried both mutations. Subsequent clinical evaluation of her brother showed evidence of retinal degeneration and peripheral visual field constriction. He remains asymptomatic; however, he is infertile. His medical history is otherwise unremarkable. Kidney function tests and ultrasound are pending.
Conclusions:
This family illustrates the high degree of variability in patients with BBS mutations and describes a novel BBS2 mutation. Mutations in BBS2 may be an under-recognized cause of apparently nonsyndromic recessive RP.
Keywords: 539 genetics •
696 retinal degenerations: hereditary •
604 mutations