Clinical Features of A Japanese Patient with Bothnia Dystrophy

Abstract

Purpose: : Bothnia dystrophy (BD) is a variant of recessive retinitis punctata albescens (RPA), caused by the homozygous R234W mutation in the RLBP1 gene. We report clinical features of a Japanese case with the homozygous R234W mutation in the RLBP1 gene.

Methods: : An affected female with RPA has been examined clinically for 25 years, and her DNA was obtained with informed consents. Exons and surrounding areas of RDH5, rhodopsin and RLBP1 genes were amplified by PCR, and direct sequencing was performed to find mutations.

Results: : 6-year-old Japanese girl was first examined in our hospital in 1986 because of night blindness at the age of 2 years. Numerous tiny white dots were observed in both eyes. Her both best-corrected visual acuities (BCVA) were (1.0). Single flash ERG showed severe reduction in both a and b wave which were markedly recovered by the extremely prolonged dark adaptation (24 hours). Visual and visual field loss started her twenties and BCVAs in 2010 (30-year-old) were (0.4) OD and (0.7) OS. Fundus examination showed the macular degeneration in both eyes. Although no mutation was detected in RDH5 and rhodopsin genes, the homozygous R234W mutation was detected in the RLBP1 gene.

Conclusions: : Clinical feature of a Japanese patient with the homozygous R234W mutation in the RLBP1 gene is very similar to that of the Swedish patients. Another Japanese case with RPA reported previously carried compound heterozygote of R103W and R234W of the RLBP1 gene. This may be caused by not the founder effect but high frequency of C to T transition.

Keywords: electroretinography: clinical • genetics • retina