Abstract
The study describes the concordance of keratoconus in 18 sets of twins. Thirteen monozygotic (MZ) and five dizygotic (DZ) pairs of twins were identified during an investigation of familial keratoconus.
The zygosity of same sex twins was confirmed by 16 forensic microsatellite markers. All of the MZ twins and four of the five DZ twins were concordant for keratoconus but with differences in age of onset and severity of disease.
The results support the currently accepted hypothesis of an important genetic contribution towards the pathogenesis of keratoconus, but suggest that there is also an environmental effect on the expression of disease.