The phenotype of Severe Early Childhood Onset Retinal Dystrophy (SECORD) from mutation of RPE65 and differentiation from Leber congenital amaurosis.
OBJECTIVE
To describe in detail the characteristic clinical phenotype and electrophysiological features of Severe Early Childhood Onset Retinal Dystrophy (SECORD) caused by mutation of RPE65.


METHODS
Ophthalmological examination, color fundus photography, visual field testing, detailed electrophysiological assessment, and screening of RPE65 were undertaken in five subjects. Selected patients also had spectral domain optical coherence tomography.


RESULTS
All five patients had life-long, extremely poor night vision. Variable degrees of nystagmus were present; three cases lacked nystagmus at the time of assessment. Bilateral disc drusen were evident in three subjects. While case 1 had an undetectable electroretinogram and features supporting a diagnosis of Leber congential amaurosis (LCA) as an infant, her level of acuity and function into the second decade of life was more consistent with SECORD. In two cases, both vision and electrophysiological responses were seen to improve into the second decade of life. The objective demonstration of improved retinal function over time, with electrophysiological testing, has not been previously reported. Cases 4 and 5 had evidence of fine white retinal dots. The authors propose that these represent abnormal accumulations of retinyl esters, as has been demonstrated in animal models, and has also been observed as lipid droplets within the retinal pigment epithelium (RPE). These white dots were seen to fade with time in the patients and were replaced by RPE changes.


CONCLUSIONS
The identification of patients with mutations in RPE65 has attained greater significance now that gene replacement trials have begun. The features presented in this article assist in the recognition of this form of LCA/SECORD.
Weleber
Richard G
RG
Oregon Retinal Degeneration Center, Oregon Health & Science University, Portland, OR, USA. weleberr@ohsu.edu
Michaelides
Michel
M
Trzupek
Karmen M
KM
Stover
Niamh B
NB
Stone
Edwin M
EM
D000293:Adolescent; D002352:Carrier Proteins / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D004596:Electroretinography; D005136:Eye Proteins / Q000235:genetics*; D005260:Female; D006801:Humans; D057130:Leber Congenital Amaurosis / Q000175:diagnosis* / Q000235:genetics; D008297:Male; D009154:Mutation; D009759:Nystagmus, Pathologic / Q000175:diagnosis / Q000235:genetics; D015594:Optic Disk Drusen / Q000175:diagnosis / Q000235:genetics; D010641:Phenotype; D058499:Retinal Dystrophies / Q000175:diagnosis* / Q000235:genetics; D041623:Tomography, Optical Coherence; D014792:Visual Acuity; D058609:Visual Field Tests; D014794:Visual Fields; D019745:cis-trans-Isomerases; D000099178:Retinoid Isomerohydrolase
D002352:Carrier Proteins; D005136:Eye Proteins; D019745:cis-trans-Isomerases; D000099178:Retinoid Isomerohydrolase