An Atypical Form of Bietti Crystalline Dystrophy

Abstract

Purpose: To describe clinical and functional features of a patient with Bietti crystalline dystrophy and atypical electroretinogram responses.

Methods: The patient underwent a thorough medical anamnesis, genetic counseling, peripheral blood draw for CYP4V2 gene analysis and electron microscopy, and a complete ophthalmological assessment including optical coherence tomography, indocyanine green angiography, microperimetry, full-field electroretinogram and multifocal electroretinogram.

Results: The most striking features of the retina were deposits of yellowish-white glistening crystals and focal lobular areas of choriocapillary atrophy at the posterior pole and midperiphery. The full-field electroretinogram was normal and the multifocal electroretinogram showed extinguished central recordings. Mutation analysis revealed a homozygous c. 332T>C p.I111T mutation in exon 3 of the CYP4V2 gene. Typical cytoplasmic inclusions containing crystalline-like structure and large degenerative lysosomes were seen on electron microscopy of peripheral leukocytes.

Conclusion: Here we describe a patient with Bietti crystalline dystrophy with a CYP4V2 gene mutation and typical leukocyte inclusions who showed the classical retinal lesions but had a normal electroretinogram. This suggests the existence of less severe forms of BCD related to relatively mild CYP4V2 mutations.

Keywords::

• bietti
• electroretinogram
• CYP4V2 gene

ACKNOWLEDGMENTS

We are grateful to Carmela Acerra for text editing.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

An earlier version of this paper, appearing online ahead of print, listed three author names incorrectly. These erroneous names (Li Anren, Zhang Jun, and Hejtmancik J. Fielding) have been corrected in this version of the paper (as Anren Li, Jun Zhang, and J. Fielding Hejtmancik).