The Role of Heredity and the Prevalence of Strabismus in Families with Accommodative, Partial Accommodative, and Infantile Esotropia

Objectives: To investigate the prevalence of strabismus in families of a proband with accommodative, partial accommodative, or infantile esotropia, and to evaluate the mode of inheritance and the role of consanguineous marriages in this prevalence. Materials and Methods: Families of probands with comitant strabismus were invited to participate in the study. The family members of 139 subjects with accommodative, 55 with partial accommodative, and 21 with infantile esotropia agreed to participate. Detailed family trees were constructed. The first- and second-degree relatives were invited for a complete ophthalmological examination, and 518 individuals from 168 families were evaluated. The role of consanguinity, the presence of tropia, phoria (≥8 PD), microtropia, and hypermetropia (≥3.00 D) among first- and second-degree relatives were analyzed. Results: A non-Mendelian pattern was found in 49 families (23%), an autosomal dominant pattern in 39 families (18%), and an autosomal recessive pattern in 6 families (3%). The prevalence of consanguineous marriages among parents of probands was 18.1%, 22.6%, and 14.3% in the accommodative, partial accommodative, and infantile esotropia groups, respectively (p=0.652). The prevalence of strabismus in first-degree relatives was 58.9%, 45.5%, and 38.1%, respectively (p=0.07). The prevalence of microtropia in probands' siblings was significantly higher in the accommodative esotropia group (p=0.034). Conclusion: Sporadic cases and non-Mendelian inheritance were more frequent than autosomal recessive inheritance. Autosomal recessive inheritance was found not to be frequent in consanguineous marriages. The prevalence of strabismus and microtropia was significantly higher in families of esotropia cases than in the general population.