Figure 2.

Locus heterogeneity in Mendelian disorders. The diagram shows the diversity of disease loci in Mendelian forms of blindness. A rough relationship between tissue and physiological complexity and the number of identified disease loci can be discerned. Data are from the Online Mendelian Inheritance in Man [30] and RetNet [31] databases. RP, retinitis pigmentosa; Usher, Usher syndrome; BBS, Bardet-Biedl syndrome.