E. L. Grigorenko1,2, F. B. Wood3,M. S. Meyer3, J. E. D. Pauls4, L. A. Hart5, D. L. Pauls1,2
Eight extended dyslexic families with at least 4 affected individuals were genotyped with twelve genetic markers spanning the Rh (rhesus factor) locus. Eleven of these markers were located on the short arm and the other was on the long arm of chromosome 1. Four theoretically derived phenotypes were used in the linkage analyses: 1) Phonemic Awareness; 2) Phonological Decoding; 3) Rapid Automatized Naming; and 4) Single Word Reading. Both parametric and nonparametric genetic analyses were completed. The statistical analyses were performed in three steps. First, pairwise linkage analyses were completed. Two chromosomal markers (D1S199 and HYTM) gave lod scores > 1 for three phenotypes: Phonemic Awareness, Decoding, and Word Identification. No positive results were obtained for the phenotype of Rapid Naming. Next, two different sets of nonparametric analyses were performed. Allele-sharing among affected relatives was examined using both identity-by-state and identity-be-descent methodologies. For pairwise analyses, both methodologies revealed significant allele-sharing in for markers D1S199 and HYTM as well as other markers in the region. When the magnitudes of the obtained effects were ordered, the strongest linkage evidence was obtained with the phenotype of Phonological Decoding. Finally, multipoint analyses were completed in an attempt to narrow down the region of significance and localize the areas of possible linkage. These results suggest that the most likely location of the putative locus is in a region near marker D1S199. This region is immediately distal to the Rh-gene.
Address: Psychology Department, Yale University, 2 Hillhouse Ave, New Haven, CT 06520, Phone: (203) 432-4660, Fax: (203) 432-7172, E-mail: elena.grigorenko@yale.edu
1Child Study Center, Yale University School of Medicine, New Haven, CT 065 10 2Department of Psychology, Yale University, New Haven, CT 06520 3Section of Neuropsychology, Department of Neurology, Bowman Gray School of Medicine, Winston-Salem, NC 27103 4Department of Biochemistry, University of Vermont, Burlington, VT 05405 5Department of Psychology, University of Pittsburgh, Pittsburgh, PA 15260