A ciliopathy is a genetic disorder of the cellular cilia or the cilia anchoring structures, the basal bodies, or of ciliary function. A ciliopathy is a genetic disorder of the cellular cilia or the cilia anchoring structures, the basal bodies, or of ciliary function. Cilia are important in guiding the process of development, so abnormal ciliary function while an embryo is developing can lead to a set of malformations that can occur regardless of the particular genetic problem. The similarity of the clinical features of these developmental disorders means that they form a recognizable cluster of syndromes, loosely attributed to abnormal ciliary function and hence called ciliopathies. Regardless of the actual cause, it is clustering of a set of characteristic features which define whether a syndrome is a ciliopathy. Although ciliopathies are usually considered to involve proteins that localize to motile and/or immotile (primary) cilia or centrosomes, it is possible for ciliopathies to be associated with unexpected proteins such as XPNPEP3, which localizes to mitochondria but is believed to affect ciliary function through proteolytic cleavage of ciliary proteins. Significant advances in understanding the importance of cilia were made in the mid-1990s. However, the physiological role that this organelle plays in most tissues remains elusive. Additional studies of how ciliary dysfunction can lead to such severe disease and developmental pathologies is still a subject of current research.