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Invest Ophthalmol Vis Sci. 1998 Nov;39(12):2417-26.

Retinal degenerations with truncation mutations in the cone-rod homeobox (CRX) gene.

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  • 1Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia 19104, USA.

Abstract

PURPOSE:

To define the phenotypes of retinal degenerations associated with mutations in the gene encoding CRX (cone-rod homeobox), a photoreceptor-specific transcription factor.

METHODS:

Heterozygotes with the E168 [delta1 bp], E168 [delta2 bp], or G217 [delta1 bp] CRXgene mutation were studied clinically, with visual function tests, including rod and cone perimetry and electroretinography (ERG), and with optical coherence tomography (OCT).

RESULTS:

Clinical diagnoses included autosomal dominant cone-rod dystrophy in one family (E168 [delta1 bp] mutation) and simplex Leber congenital amaurosis in two families (E168 [delta2 bp], G217 [delta1 bp] mutations). In the family with the E168 [delta1 bp] mutation, two siblings had relatively mild disease expression in the third decade of life. The central retinas of these two patients had profound loss of rod and short wavelength cone function; long/middle wavelength cone thresholds were elevated at fixation, but there were greater paracentral than central abnormalities. Peripheral retinal dysfunction was evident by psychophysics and by maximum amplitude loss for rod- and cone-isolated ERG photoreceptor responses. OCT cross-sectional reflectance images showed decreased central retinal thickness consistent with photoreceptor loss. An additional member of this family (E168 [delta1 bp] mutation) and two other patients (representing E168 [delta2 bp] and G217 [delta1 bp] mutations) had a severe phenotype with retina-wide loss of function and islands of function remaining only in the temporal periphery.

CONCLUSIONS:

Truncation mutations in CRX are associated with retinopathies that share phenotypic features but vary in disease severity. The disease mechanism could involve abnormal photoreceptor development compounded by a disturbance in the maintenance of photoreceptors in the mature retina.

PMID:
9804150
[PubMed - indexed for MEDLINE]
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