PURPOSE: The concordance of strabismic phenotypes was examined in monozygotic versus multizygotic twins and other multiple births to study the role of genetic background in different types of commitant strabismus. METHODS: Medical charts of 45 consecutive pairs of twins (16 monozygotic and 18 dizygotic twins, and 11 with unknown zygosity), 3 sets of triplets (one monozygotic and 2 trizygotic triplets), and one set of quadruzygotic quadruplets examined at 6 institutions between 1973 and 1999 were reviewed retrospectively. The concordance was defined as both or all members having either esotropia or exotropia in common. RESULTS: The concordance of strabismic phenotypes was noted in 33 of 49 pairs or sets (67.3%): 14 of 17 monozygotic twins or triplets (82.4%), 10 of 21 multizygotic twins, triplets, or quadruplets (47.6%), and 9 of 11 twins with unknown zygosity (81.8%). The concordance rate was significantly higher in monozygosity than in multizygosity (P =.043, Fisher exact probability test). The predominant concordant phenotypes in monozygosity were accommodative esotropia and intermittent exotropia. CONCLUSION: A high concordance rate of strabismic phenotypes, predominantly of accommodative esotropia and intermittent exotropia in monozygosity, suggests the genetic background for these types of strabismus.
PURPOSE: The concordance of strabismic phenotypes was examined in monozygotic versus multizygotic twins and other multiple births to study the role of genetic background in different types of commitant strabismus. METHODS: Medical charts of 45 consecutive pairs of twins (16 monozygotic and 18 dizygotic twins, and 11 with unknown zygosity), 3 sets of triplets (one monozygotic and 2 trizygotic triplets), and one set of quadruzygotic quadruplets examined at 6 institutions between 1973 and 1999 were reviewed retrospectively. The concordance was defined as both or all members having either esotropia or exotropia in common. RESULTS: The concordance of strabismic phenotypes was noted in 33 of 49 pairs or sets (67.3%): 14 of 17 monozygotic twins or triplets (82.4%), 10 of 21 multizygotic twins, triplets, or quadruplets (47.6%), and 9 of 11 twins with unknown zygosity (81.8%). The concordance rate was significantly higher in monozygosity than in multizygosity (P =.043, Fisher exact probability test). The predominant concordant phenotypes in monozygosity were accommodative esotropia and intermittent exotropia. CONCLUSION: A high concordance rate of strabismic phenotypes, predominantly of accommodative esotropia and intermittent exotropia in monozygosity, suggests the genetic background for these types of strabismus.
Authors: Sherin Shaaban; Sarah MacKinnon; Caroline Andrews; Sandra E Staffieri; Gail D E Maconachie; Wai-Man Chan; Mary C Whitman; Sarah U Morton; Seyhan Yazar; Stuart MacGregor; James E Elder; Elias I Traboulsi; Irene Gottlob; Alex W Hewitt; David G Hunter; David A Mackey; Elizabeth C Engle Journal: Invest Ophthalmol Vis Sci Date: 2018-08-01 Impact factor: 4.799