Linkage studies in a large stuttering family indicate multiple novel loci and possible assortative mating. A. A. Schaffer1, M. H. Raza2, E. M. Gertz1, J. Mundorff2, J. Lukong2, J. Kuster3, D. Drayna2 1) National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD USA; 2) National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD USA; 3) Department of Speech, Hearing, and Rehabilitative Services, Minnesota State University, Mankato, MN.

   Stuttering is a common speech disorder that is a complex trait with high heritability. While linkage studies in consanguineous populations have produced highly significant evidence for linkage at a number of loci, such studies in outbred populations have been less successful. We have ascertained a large family with many cases of persistent stuttering from Cameroon, West Africa in which consanguinity is denied. An initial genome-wide linkage scan using microsatellites that tested the complete pedigree for linkage produced a suggestive score on chromosome 1. However subsequent linkage scans with SNPs that analyzed the complete family failed to confirm this linkage, and no significant linkage scores were observed genome-wide. In contrast, dividing the pedigree into five branches and analyzing individual branches and combinations of branches produced strong evidence for linkage with both SNP and microsatellite markers. In this family, we found evidence for linkage to previously reported loci on 3q and 15q, and to novel loci on 2p, 3p, 14q, and a different position on 15q. While the mechanism by which these multiple alleles came together in the same family is unknown, we found little evidence for consanguinity, and we suggest assortative mating as a likely explanation. Such assortative mating has been shown to be important in the epidemiology of hereditary deafness, and may play a role in the epidemiology of stuttering.

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