Clinical features of a Japanese case with Bothnia dystrophy

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

An affected woman with RPA has been examined clinically for 25 years. Her DNA was obtained with informed consent, and the exons and surrounding areas of RDH5, rhodopsin, and RLBP1 were amplified by PCR and directly sequenced.

Our patient was first examined in our hospital in 1986 when she was 6 years old. Ophthalmoscopy showed numerous small white dots in the posterior pole of both eyes. Although the a- and b-waves of the single flash ERGs were severely reduced after a standard 30 min of dark-adaptation, the amplitudes of both waves increased markedly after 24 hr of dark-adaptation. The visual disturbances and visual field scotomas became more evident in her twenties, and her BCVAs were 0.2 OD and 0.5 OS when she was 31 years old in 2010. Fundus examinations showed macular degeneration in both eyes. A homozygous R234W mutation was detected in RLBP1, and no mutations were detected in RDH5 and rhodopsin.

The clinical characteristics of a Japanese patient with a homozygous R234W mutation in RLBP1 are very similar to that of Swedish patients with Bothnia dystrophy. The origin of the Japanese R234W mutation is probably not the same as that of the Swedish patients, but more likely due to the high incidence of C to T transitions.