Cheryl Y Gregory-Evans

Section of Cell and Molecular Biology, Division of Biomedical Sciences, Faculty of Medicine, Imperial College, London SW7 2AZ, UK

Retinal dystrophies are one of the most heterogeneous group of diseases thus far examined. This makes molecular and clinical diagnostics very complex, but at the same time provides fascinating insight into the functional aspects of the retina. A clinically based nomenclature system does not correlate neatly with molecular reality at the DNA level because three types of heterogeneity are commonly observed in retinal dystrophies: (1) genetic heterogeneity, referring to mutations in different genes causing the same disease, (2) allelic heterogeneity, referring to different mutations in the same gene causing different diseases, and (3) clinical heterogeneity, referring to the same gene mutation causing different symptoms in different individuals, even within the same family. Another level of complexity has recently begun to emerge in that different mutations in the same gene can be inherited by different Mendelian mechanisms. Five genes that exhibit different modes of inheritance of mutations are rhodopsin, PDEB, GUCY2D, RDS and CRX, which will be discussed in detail. Clearly, as new disease genes are identified they should be assessed as potential candidates for both autosomal dominant and recessively inherited diseases. This complexity also has a bearing on genetic counseling, particularly for the CRX gene mutations.

Copyright © Deutsche Ophthalmologische Gesellschaft, 2001. All rights reserved.

Last updated: 

Webdesign: SPALLEK.COM