Usher syndrome: results of a screening program in Colombia.

Otological, ophthalmological and genetic studies were performed in 46 patients with Usher syndrome, identified through a screening program in Colombia. Of them, 69.6% had Usher syndrome type I, 26.1% type II, and 4.3% type III. Thirty-three patients showed profound deafness (71.7%), while 13 (28.3%) had moderate to severe hearing loss. The ophthalmologic manifestations showed marked variability. Although the majority of the patients had serious ocular impairment before age 20, 32.6% had good central visual acuity. The prevalence of Usher syndrome in Colombia, estimated at 3.2/100,000, warrants the implementation of screening programs in schools for the deaf and for the blind. Our study confirms that Usher syndrome shows no geographic or racial variation and that the disorder has a wide variability of expression and genetic heterogeneity. The large size of the families we have detected may provide important opportunities for further genetic studies, particularly in terms of the assignment of the locus and gene mapping.