Two families from New England with Usher syndrome type IC with distinct haplotypes

PURPOSE: To search for patients with Usher syndrome type IC among those wit h Usher syndrome type I who reside in New England. METHODS: Genotype analysis of microsatellite markers closely linked to the USH1C locus was done using the polymerase chain reaction. We compared the h aplotype of our patients who were homozygous in the USH1C region with the h aplotypes found in previously reported USH1C Acadian families who reside in southwestern Louisiana and from a single family residing in Lebanon, RESULTS: Of 46 unrelated cases of Usher syndrome type I residing in New Eng land, two were homozygous at genetic markers in the USH1C region. Of these, one carried the Acadian USH1C haplotype and had Acadian ancestors (that is , from Nova Scotia) who did not participate in the 1755 migration of Acadia ns to Louisiana, The second family had a haplotype that proved to be the sa me as that of a family with USH1C residing in Lebanon, Each of the two fami lies had haplotypes distinct from the other. CONCLUSION: This is the first report that some patients residing in New Eng land have Usher syndrome type IC, Patients with Usher syndrome type IC can have the Acadian haplotype or the Lebanese haplotype compatible with the id ea that at least two independently arising pathogenic mutations have occurr ed in the yet-to-be identified USH1C gene. (Am J Ophthalmol 2001;131:355-35 8, (C) 2001 by Elsevier Science Inc. All rights reserved.).