Novel CYP4V2 gene mutation in a Mexican patient with Bietti's crystalline corneoretinal dystrophy.
OBJECTIVE
To report the clinical and genetic analysis of a Mexican female patient with a sporadic Bietti's crystalline corneoretinal dystrophy.


METHODS
Ophthalmological examination included best-corrected visual acuity, slit lamp examination, applanation tonometry, fundus photography, fluorescein retinal angiography, Goldmann kinetic perimetry, corneal rotating Scheimpflug imaging, and anterior segment optical coherence tomography (Visante OCT). Genetic analysis included PCR amplification and direct nucleotide sequencing of the entire CYP4V2 gene in DNA from the propositus and her relatives.


RESULTS
A late-stage retinal dystrophy was established in the patient. No retinal or corneal crystalline deposits were evident during clinical evaluation. Retrospective analysis of fundus imaging disclosed the presence of retinal crystalline deposits, suggesting the diagnosis of Bietti's crystalline corneoretinal dystrophy. Molecular analysis of the CYP4V2 gene revealed the presence of a novel C to T mutation at nucleotide position 974 (exon 7), predicting a threonine to isoleucine replacement at amino acid position 325. Corneal deposits were not seen by biomicroscopy, corneal OCT, or specular microscopy but were evidenced by means of the corneal rotating Scheimpflug imaging.


CONCLUSIONS
Our results expand the allelic heterogeneity of Bietti's crystalline corneoretinal dystrophy. This is the first patient of Latin-American origin in which a molecular analysis of the disease has been performed. Our results suggest that the use of corneal rotating Scheimpflug imaging can evidence corneal deposits that are not apparent by other methods.
Zenteno
Juan C
JC
Department of Genetics and Research Unit, Institute of Ophthalmology Conde de Valenciana, Mexico City, Mexico. jczenteno@institutodeoftalmologia.org
Ayala-Ramirez
Raul
R
Graue-Wiechers
Federico
F
D000368:Aged; D019943:Amino Acid Substitution; D003317:Corneal Dystrophies, Hereditary / Q000208:ethnology / Q000235:genetics* / Q000473:pathology; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics*; D000072470:Cytochrome P450 Family 4; D003596:Cytosine; D003941:Diagnostic Techniques, Ophthalmological; D005260:Female; D005654:Fundus Oculi; D006801:Humans; D007198:Indians, North American / Q000235:genetics*; D007532:Isoleucine; D008800:Mexico; D009154:Mutation; D012164:Retinal Diseases / Q000208:ethnology / Q000235:genetics* / Q000473:pathology; D013912:Threonine; D013941:Thymine
D007532:Isoleucine; D013912:Threonine; D003596:Cytosine; D003577:Cytochrome P-450 Enzyme System; C505357:CYP4V2 protein, human; D000072470:Cytochrome P450 Family 4; D013941:Thymine