An integrated genetic approach to identify candidate genes for human chromosome 6q-linked retinal disorders.

Abstract

In recent years the field of retinal gene discovery has experienced an explosion. An estimated 10,000-30,000 genes are thought to be expressed in the human retina (Shimizu-Matsumoto et al., 1997), with nearly 5,000 retinal transcripts catalogued from expressed sequence tag (EST) datasets (Bortoluzzi et al., 2000) and over 26,000 different transcripts represented in retina serial analysis of gene expression (SAGE) libraries (Sharon et al, 2002). A wide variety of methods have been developed and utilized to define novel retinal genes, particularly in an effort to identify genes targeted in human retinopathies. To date there are 144 diseases of the retina described that have been mapped to human chromosomal locations, and an additional 41 human disorders involving some form of retinal dystrophy for which the genetic map locations have yet to be determined (RetNet Retinal Information Networkhttp://www.sph.uth.tmc.edu/retnet/;Online Mendelian Inheritance in Man (OMIM)http://www.ncbi.nlm.nih.gov/omim/). Despite recent efforts to discover novel genes by analyzing increasingly greater volumes of information arising from human genomic sequence data organization and expression studies, the disease genes for less than one-half of these conditions have at present been cloned. While some of these disorders may be attributed to allelic heterogeneity, a significant number of genes that account for retinal degenerative phenotypes remain to be defined.