Genetic aspects of strabismus

Abstract

Arq Bras Oftalmol 2002;65: Purpose: To evaluate the genetic aspects of strabismus. Methods: Ophthalmic and orthoptic evaluations were performed prospectively on 110 strabismic probands and 478 relatives. We used 3 different criteria in the diagnosis of strabismus: primary diagnosis (dx1) defined as any manifest horizontal or vertical deviation, a secondary diagnosis (dx2) including esophoria (>7 prism diopters) or exophoria (>9 prism diopters), and a tertiary diagnosis (dx3) including abnormal fusional amplitudes, accommodative convergence/accommodation (AC/A) ratio, and/or stereopsis; monofixation syndrome; 4 prism diopters base out; and/or abnormal Maddox test responses. Analyses were carried out within mating types. Results: Hypotheses of autosomal dominant or recessive inheritance with no sporadics were rejected. Based on the dx1, 25% of the families had more than one individual affected and there was vertical transmission in 13%; adding dx2 there were 36% of the families with more than one affected and 21% had vertical transmission; and adding dx3, there were 73% with more than one affected and 51% with vertical transmission. Conclusions: There is evidence for a pattern consistent with an autosomal dominant form of strabismus in most families. Aspectos genéticos em estrabismo

Genetic and environmental contributions to strabismus and phoria: Evidence from twins

“…As shown graphically in Figure 1a, the correlation in liability calculated from extant DZ twin data was the tetrachoric correlation coefficient r(130)=0.46 (+-SE=0.37-0.54). The parallel tetrachoric correlation in first-degree relatives was r(3525)=0.29 (+-SE=0.26-0.31) [we calculated this correlation from a strabismus prevalence in the general population of 3.9% (see above; Robaei, Rose et al, 2006) and a strabismus risk given an affected first-degree relative of 13.4% (95% CI 12.3-14.6%; based on 473 of 3,526 affected first-degree relatives of strabismics reported by eight studies: Aurell & Norrsell, 1990; Cantolino & von Noorden, 1969; Crone & Velzeboer, 1956; Ferreira, Oelrich & Bateman, 2002; Griffin, Asano, Somers & Anderson, 1979; Podgor, Remaley & Chew, 1996; Richter, 1967; Ziakas, Woodruff, Smith & Thompson, 2002)]. Assuming the larger correlation in DZ twins than first-degree relatives (Fisher z=2.2, p=0.01) was not solely due to age-discrepancy-caused discordance among first-degree relatives, these correlations suggest an environmental effect that interacts with pre-existing genetic liability.…”

Risk Factors and Genetics in Common Comitant Strabismus

“…Six studies considered inheritance of strabismus throughout families [31][32][33][34][35][36] (Table 2), 2 of which recruited probands with esotropia; 1, IET; and 4 combined both exotropia and esotropia. True concordance of the type of strabismus has been difficult to assess because of missing information in a large number of the pedigrees; however, in 1 study, in those who could be assessed, 80% had concordance.…”

“…32 This was further supported by a later study that found that in 53.9% of families only 1 type of squint occurred (esotropia or exotropia) compared with 46.1% that had both. 35 X-linked inheritance was evaluated by 6 studies but quickly rejected as the mode of inheritance for strabismus because of a similar number of affected males and females and significant male to male transmission. [31][32][33][34][35][36] Recessive and dominant models also produced conflicting results.…”

“…35 X-linked inheritance was evaluated by 6 studies but quickly rejected as the mode of inheritance for strabismus because of a similar number of affected males and females and significant male to male transmission. [31][32][33][34][35][36] Recessive and dominant models also produced conflicting results. [32][33][34][35][36] The majority of studies propose a polygenic inheritance where multiple factors, genetic and environmental, are involved because inheritance patterns cannot be fully explained by simple mendelian models.…”

“…[31][32][33][34][35][36] Recessive and dominant models also produced conflicting results. [32][33][34][35][36] The majority of studies propose a polygenic inheritance where multiple factors, genetic and environmental, are involved because inheritance patterns cannot be fully explained by simple mendelian models. [31][32][33]36 Dominant inheritance with esotropia when compared with exotropia has been reported in 1 study by Schlossman and Priestley.…”