[What can we learn from molecular genetic analyses of inherited eye diseases?]

Over the past decade, the pace of gene identification of the causes of inherited eye diseases has increased dramatically as the complete human genome information becoming available. Molecular genetic analysis establishes reliable clinical diagnostic criteria and improves the accuracy of diagnosis. We encountered two atypical cases, a patient who had only bilateral band-shaped opacities without any gelatinous prominences, and a patient who had diffuse central corneal stromal opacity without any lattice lines. The diagnosis of gelatinous drop-like dystrophy and lattice corneal dystrophy I was confirmed by molecular genetic analysis of TACSTD2 and TGFBI, respectively. We confirmed the existence of a predominantly ocular type of stickler syndrome by identifying the mutation involving exon 2 of the COL2A1 gene in a Japanese patient who had received a diagnosis of rhegmatogenous retinal detachment. We surmise that in Japan in the past, this diagnosis may have been overlooked or misdiagnosed as Wagner disease. Molecular genetic analysis is also useful for gaining a better understanding of diseases. We detected a novel FZD4 mutation in a patient with familial exudative vitreoretinopathy who exhibited peripheral avascular areas bilaterally, a dragged disk, and retinal holes unilaterally, suggesting that FZD4 may be involved in the angiogenesis of the human peripheral retina. Molecular genetic analysis of a Japanese patient with pseudoxanthoma elasticum with choroidal neovascularization revealed a homozygous nonsense mutation in the ABCC6, a member of the ABC transporter family, indicating that angioid streaks may be caused by a primary metabolic disorder. The development of rapid and comprehensive genotyping systems using state-of-the-art technology such as genotyping microarray may eventually offer unique and reliable diagnostic tools. This should then accelerate our understanding of the basic mechanisms underlying inherited eye diseases and their phenotypic variability, thus facilitating prospective diagnosis.