RP1L1 Mutation In Korean Patients Of Occult Macular Dystrophy (OMD)

Abstract

Purpose: : RP1L1 gene mutation has been reported to be responsible for dominantly inherited occult macular dystrophy (OMD) in Japanese population. We investigated the same mutation of RP1L1 in Korean patients with OMD and searched genotype-phenotype correlations using multimodal imaging modalities.

Methods: : In 14 eyes from 7 Korean patients diagnosed as OMD, detailed retinal morphologic abnormalities were evaluated by spectral-domain optical coherence tomography (SD-OCT), fundus infrared (IR) reflectance, autofluorescence (AF), and IR-AF imaging. DNA from peripheral blood was extracted and direct sequencing was performed on the entire exons and flanking regions of the RP1L1 gene in all patients.

Results: : Out of 7 patients, mutation of RP1L1 (p.Arg45Trp) which was previously reported in Japanese OMD patients was found in 4 patients (57.1%) of 3 families. All patients with RP1L1 mutation had family history and showed symmetric photoreceptor disruption centered on fovea in both eyes on SD-OCT. Whereas, patients without RP1L1 mutation were sporadic and showed asymmetric photoreceptor disruption not centered on fovea. In 2 of 3 patients without the mutation, unilateral involvement was noted while all patients with mutation were bilateral. IR imaging showed round hyporeflectance centered on fovea in all patients with RP1L1 mutation whereas irregular hyporeflectance was observed in patients without mutation. The fundus AF and IR-AF images in OMD did not have any pathognomonic abnormalities, regardless of the genetic mutation.

Conclusions: : RP1L1 p.Arg45Trp mutation was replicated in Korean hereditary OMD patients. The presence of RP1L1 mutation in about half of OMD patients and the distinctive features on SD-OCT and IR imaging indicates OMD is a heterogeneous disease.

Keywords: retinal degenerations: hereditary • genetics