Consanguinity and its association with visual impairment in southern India: the Pavagada Pediatric Eye Disease Study 2.

To determine the association of consanguinity with the occurrence of genetically transmitted eye diseases in rural and urban populations in Pavagada and Madhugiri taluks, Karnataka state, south India. This study was part of a population based cross-sectional prevalence survey, "The Pavagada pediatric eye disease study 2." As a part of the demographic data, trained investigators collected information on consanguinity from the parents of children identified for the study. The children underwent visual acuity measurements and were examined by an ophthalmologist. Children with minor eye diseases were treated and those with major eye diseases were seen by a pediatric ophthalmologist. Eight thousand five hundred and fifty-three children were examined. The prevalence of ocular morbidity was 6.54% and blindness was 0.09%. The percentage of consanguineously married couples in the screened population was 34.33%. Among the blind children, 75% were blind with a disease with potential genetic etiology. Out of that, 66.67% were born out of consanguineous marriage (uncle-niece). Among children with diseases with a potential genetic etiology 54.29% of the children were born out of consanguineous union. Most of these children (71.43%) were born out of uncle-niece marriages. Further analysis showed that consanguineous parents were more likely to have children with disease with a potential genetic etiology as compared to nonconsanguineous parents (odds ratio: 2.551, p = 0.012). It is evident that consanguineous marriages, especially uncle-niece unions are common in the study area. Consanguinity is more likely to result in children with eye diseases with potential genetic etiology.