Abstract
Purpose: :
To describe the clinical and genetic characteristics of 7 Japanese families with Bietti’s crystalline corneoretinal dystrophy (BCD).
Methods: :
Mutation screening was performed on 7 unrelated patients with BCD by direct sequencing. The clinical features were characterized by the visual acuity, slit–lamp biomicroscopy, electroretinography, fluorescein angiography, and kinetic visual field testing.
Results: :
An identical IVS6–8delTCATACAGGTCATCGCG/insGC mutation in the CYP4V2 gene was identified in 6 of the patients with BCD, and the seventh patient had a novel Trp340X mutation in the CYP4V2 gene. The IVS6–8delTCATACAGGTCATCGCG/insGC mutation was at the 3’splice site in exon 7 and resulted in the skipping of exon 7. The initial symptom of patients with BCD was a decrease of visual acuity in 3 of the patients, night blindness in 3, and a constricted visual field in one patient. The visual acuity of the patients ranged from 0.03 to 1.5. Three patients showed crystalline–like deposits at the limbus by specular microscopy. Ten year clinical observations of three patients associated with the IVS6–8delTCATACAGGTCATCGCG/insGC mutation disclosed that patients over 50 years had advanced choroidal sclerosis, decrease or absence of crystalline deposits, decreased visual acuity, and attenuation of retinal vessels. Also all patients had a rapid progression after age 50 years.
Conclusions: :
Our findings suggest that the IVS6–8delTCATACAGGTCATCGCG/insGC mutation is a common mutation in Japanese patients with BCD. Although phenotypic variability was found, the natural course was almost the same in all of our patients.
Keywords: candidate gene analysis • mutations • retinal degenerations: hereditary