Abstract
Purpose: :
To identify and characterize the gene mutation responsible for photoreceptor degeneration in the rd3 mouse.
Methods: :
We screened genes in the known rd3 (RBF/DnJ) mapped region by direct sequencing. We additionally screened other rd3 lines (RBJ/Dn, STOCK Rb(11.13)4Bnr/J and STOCK In(5)30Rk) and normal mouse strains to verify the alteration. We carried out a mutation screen of the human RD3 gene in patients with retinopathies and examined 431 patients of Caucasian ethnicity and 103 of Asian–Indian ancestry. Amino acid changes that were identified in patients but not in controls are being examined by immunoblot analysis and immunocytochemisty to determine their effect(s) on protein stability or localization.
Results: :
The rd3 mutation is a homozygous C to T transition, leading to a stop codon, which is predicted to result in a premature truncation of the rd3 protein. The mutation was present in all rd3 lines tested (RBF/DnJ, RBJ/Dn, 4bnr and IN–30) but not in the control lines (C57BL/6J, A/J, AE/J, BALB/cJ, C3H/HeJ, CBA/J, DBA/2J, MOLC/Rk, NON/Lt) examined. The human mutation screen is ongoing. We have identified two putative homozygous alterations, which may affect the RD3 protein. Additional studies are in progress.
Conclusions: :
The rd3 mouse is among the oldest known mouse models of retinal degeneration. The elucidation of the mutation leading to the disease phenotype will have implications for retinal degenerative disease in humans.
Keywords: retina • genetics • mutations