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H. Fujiwara, T. Matsuo, M. Sato, T. Yamane, M. Kitada, S. Hasebe, H. Ohtsuki; Genome-wide Search for Comitant Strabismus Susceptibility Loci . Invest. Ophthalmol. Vis. Sci. 2003;44(13):2753.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Epidemiological and twin studies suggested a genetic background for comitant strabismus. However, no genes or even no chromosomal loci have yet been elucidated in comitant strabismus. In this study, we tried to find chromosomal susceptibility loci for comitant strabismus by genome-wide search. Methods: Genomic DNA was isolated from 10 mL peripheral blood obtained from two or three children, together with either father or mother or both in each of 30 nuclear families. At least two children in each family had either esotropia or exotropia. Exotropia, including intermittent exotropia and constant exotropia, was found as a common manifestation in 13 sib-pairs, while esotropia, including infantile esotropia, accommodative esotropia, esophoria, and unclassified esotropia, was found as common in 12 sib-pairs. In three sib-pairs, one sibling had exotropia while the other had esotropia. One sib-pair consisted of one sibling with exotropia and the other with vertical comitant strabismus. One sib-pair comprising one sibling with accommodative esotropia and the other only with hyperopia was included in this analysis since hyperopia is a well-known risk factor for the development of accommodative esotropia. Genome-wide search was done with amplification by polymerase chain reaction of 400 markers in microsatellite regions with an about 10 cM resolution. Non-parametric affected sib-pair analysis and non-parametric linkage analysis for multiple pedigrees in Genehunter software (http://linkage.rockefeller.edu/soft/) were used to calculate multipoint lod scores and non-parametric linkage (NPL) scores, respectively, for each locus. Results: In sib-pair analysis, multipoint lod scores showed basically flat lines with some peaks only as high as 0.25 on all chromosomes. In non-parametric linkage analysis for multiple pedigrees, one peak of NPL scores as high as 1.34 was found on each of chromosome 1, 2, 4, 7, and 10, while two peaks of NPL scores as high as 1.34 were found on each of chromosome 3, 9, 11, 12, and 18. These NPL scores, however, did not reach a statistical significance. The remaining chromosomes did not have any peak with an NPL score of 1 or greater. Conclusions: Non-parametric linkage analysis for multiple pedigrees including 30 families with comitant strabismus suggested a number of chromosomal susceptibility loci. Our ongoing study involving a larger number of families would refine the accuracy of statistical analysis to reach the susceptibility loci for comitant strabismus.
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