Fig. 1. A diagram demonstrating two molecular detection techniques. Allele-specific hybridization (top) for the detection of point mutations in the rhodopsin gene in patients with autosomal-dominant retinitis pigmentosa. The dark spots represent DNA containing mutations at codon 23 of the rhodopsin gene. Electrophoretic pattern (bottom) demonstrating the nonradioactive single-strand conformational polymorphism technique. The leftmost lane corresponds to a retinoblastoma gene fragment containing a point mutation, resulting in altered motility compared with the rest of lanes with normal DNA. (Adapted from Wang MX, Donoso LA: Gene research and the eye. Curr Opin Ophthalmol 4(III): 102, 1993)