Primary cilia

Article By:

Mykytyn, Kirk Departments of Pharmacology and Internal Medicine, Division of Human Genetics, Ohio State University, Columbus, Ohio.

Green, Jill A. Departments of Pharmacology and Internal Medicine, Division of Human Genetics, Ohio State University, Columbus, Ohio.

Last reviewed:2012

DOI:https://doi.org/10.1036/1097-8542.YB120225

On nearly every cell type in the human body, a tiny hairlike organelle known as a primary cilium protrudes from the cell surface. These cellular appendages act as specialized antennae to survey the extracellular milieu and transmit signals into the cell that are essential for cellular homeostasis. Primary cilia were discovered in the late 1890s and were originally considered evolutionary remnants. However, interest in these organelles has increased dramatically over the past decade as a result of the recognized link between primary cilia and human disease. Improper formation or function of primary cilia can result in a myriad of human diseases and genetic disorders that are collectively called ciliopathies. Due to the ubiquity of cilia, ciliopathies can present with a wide range of clinical features, including obesity, cystic kidney disease, blindness, polydactyly (the condition of having supernumerary fingers or toes), cognitive deficits, behavioral disturbances, hypogonadism, and brain malformations (see table). The pathophysiological consequences of dysfunction of primary cilia highlight the important roles that cilia play during development and in the normal function of most tissues. Although great progress has been made in understanding the functions of primary cilia for some cell types, primary cilia function for most cell types is still not known.

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