Compound heterozygous RDH5 mutations in familial fleck retina with night blindness

To describe the clinical features and genetic analysis of a 3-year-old boy diagnosed with familial fleck retina with night blindness.

The proband and his parents and grandparents were included. History, visual acuity and fundus examinations were evaluated. Bright-flash (rod-plus-cone) electroretinograms (ERGs) were recorded after 30 mins and 180 mins of dark adaptation. Mutation screening of the RDH5 gene encoding 11-cis retinol dehydrogenase was performed.

The parents noticed the proband's night blindness when he was 2 years old. Best corrected visual acuity was 1.0 in both eyes. Fundus examinations revealed numerous yellow-white flecks of varying size and shape throughout the midperipheral to far peripheral retina in both eyes. The distribution, size and shape of the flecks were comparable to those seen in familial fleck retina with night blindness, rather than fundus albipunctatus. The ERGs showed extremely diminished responses after 30 mins of dark adaptation, but there were substantial increases in the amplitudes of both a- and b-waves when recorded after 180 mins of dark adaptation. Although a total of 19 RDH5 mutations have been found only in patients with fundus albipunctatus, compound heterozygous mutations, p.V177G and p.L310delinsEV, whose combination has not been previously reported, were found in the proband. The asymptomatic parents and one of the grandparents each carried one of the mutations, consistent with autosomal recessive transmission.

Our study indicates that different mutations in the RDH5 gene can cause phenotypic variations of either fundus albipunctatus or familial fleck retina with night blindness.