Novel variants in familial exudative vitreoretinopathy patients with KIF11 mutations and the Genotype-Phenotype correlation.

Familial exudative vitreoretinopathy (FEVR) is an inherited disease characterized by abnormal development of retinal vasculature. KIF11 mutations were identified to be associated with FEVR in recent years. The purpose of this study was to investigate novel variants and describe associated ocular and extraocular phenotypes in FEVR patients with KIF11 mutations. Herein, 417 probands with clinical diagnosis of FEVR were enrolled. Genetic testing and ophthalmic examinations were performed in all subjects, and the genotype-phenotype correlation was analyzed. Overall, KIF11 mutation was identified in nine probands (9/417, 2.2%) among the patients with FEVR phenotype. There were six males and three females whose median age was six months (range: four months to six years old) at first visit. Among the detected mutations, five (55.6%) were frameshift, two (22.2%) were missense, one (11.1%) nonsense, and one (11.1%) splicing. Seven of these KIF11 mutations were detected as novel. Four (4/9, 44.4%) of the mutations were de novo. Clinical examinations showed that: four probands presented with bilateral falciform retinal fold; two with bilateral tractional retinal detachment; one was observed tractional retinal detachment in one eye and retinal fold in the other eye; one had falciform retinal fold in one eye and chorioretinal atrophy in the other eye; one exhibited rhegmatogenous retinal detachment in the left eye. Six of the probands were detected to have microcephaly. In conclusion: Most (5/9,55.6%) of the causative mutations were frameshift, and nearly half (4/9, 44.4%) of the mutations were de novo. Most (8/9, 88.9%) patients with KIF11 mutations showed typical ocular manifestations of severe FEVR. Majority (6/9, 66.7%) of the probands had a KIF11 mutation and were detected to have microcephaly. Seven of these harbored KIF11 mutations detected to be novel.