Keratoconus(KC)is a progressive disease characterized by gradual corneal thinning and ectasia, resulting in irregular astigmatism, myopia, and mild to severe visual impairment. Although the pathogenesis of KC is still unclear, twin studies and family-based studies have identified that the occurrence of KC is closely related to genetic factors. First-degree relatives of KC patients including their parents, siblings and offspring are very important for the family aggregation analysis and polygenic analysis of diseases. This review summarized the current situation of clinical and genetic research about first-degree relatives of KC patients, hoping to deepen the understanding of clinical manifestations and genetic characteristics of first-degree relatives of KC, and to provide new ideas for exploring the role of genetic and environmental factors in the pathogenesis of KC.