To search for mutations in the Frizzled-4 gene (FZD4) in Chinese patients with familial exudative vitreoretinopathy (FEVR) and to delineate the mutation-associated clinical features.
Forty-eight Chinese patients with FEVR and 100 unrelated control subjects were recruited and had complete ophthalmic examinations performed. The coding regions of FZD4 were screened for mutations by polymerase chain reaction and direct sequencing. Multiple sequence alignment was conducted to evaluate the conservation of residues among different FZD4 homologs and the human Frizzled family. Genotype-phenotype correlations were also analyzed.
Twelve putative disease-causing mutations were identified in total, 9 of which were novel: 1 deletion (P14fsX57), 1 nonsense mutation (S491X), and 7 missense mutations (G22E, E180K, T237R, R253C, F328S, A339T, and D470N). Three reported FZD4 mutations were also detected: H69Y, M105V, and W496X. Remarkably, 2 patients who harbored compound heterozygous mutations (H69Y with E180K or W496X) had a more severe ocular phenotype than carriers of a single H69Y mutation.
FZD4 mutations were responsible for FEVR in 15 of 48 Chinese patients (31.3%) in this study, similar to other ethnic groups. This study supports the highly polymorphic nature of FZD4 with a differential mutation profile in the Chinese population.
The profile of the mutations obtained in FZD4 further illustrates the complexity of FEVR and provides a better understanding of the genotype-phenotype correlations.