A high association with cone dystrophy in Fundus albipunctatus caused by mutations of the RDH5 gene.

PURPOSE

To analyze the RDH5 gene in patients with fundus albipunctatus with and without cone dystrophy and to determine whether the disease is stationary or progressive and whether the cone dystrophy is a part of fundus albipunctatus or a separate disease.

METHODS

Fourteen patients from 12 separate Japanese families with fundus albipunctatus were examined. Six of the patients from 6 families also had a cone dystrophy. Genomic DNA was extracted from leukocytes of the peripheral blood, and exons 2, 3, 4, and 5 of the RDH5 gene were amplified by polymerase chain reaction and were directly sequenced. A complete ophthalmic examination was performed including best-corrected visual acuity, slit-lamp examination, indirect ophthalmoscopy, fundus photography, and electroretinography.

RESULTS

In all the patients, either a homozygous mutation or compound heterozygous mutations in the RDH5 gene were identified. The identified mutations were nucleotide position (nt) 103 G to A (Gly35Ser), nt 319 G to C (Gly107Arg), nt 394 G to A (Val132Met), nt 719 G insertion (frame shift), nt 839 G to A (Arg280His), nt 841 T to C (Tyr281His), and nt 928 C to GAAG (Leu310 to GluVal). All these mutations except the Arg280His were new. The nt 928 C to GAAG mutation was detected in patients with and without cone dystrophy. Cone dystrophy was most frequently seen in patients over 40 years old.

CONCLUSIONS

Fundus albipunctatus either with or without cone dystrophy is caused by mutations of the RDH5 gene. Cone dystrophy is frequently observed in elderly patients with fundus albipunctatus. The conclusion was reached that the mutations of the RDH5 gene caused a progressive cone dystrophy as well as night blindness.