The CC2D2A gene encodes a protein that forms a part of the tectonic complex. This complex is localized at the ciliary transition zone and prevents the diffusion of transmembrane proteins between the cilia and plasma membranes. Based on studies in lower species, the protein is believed to be involved in a number of biological processes, including primary cilium assembly, determination of left/right symmetry and embryonic brain development.
The CC2D2A gene is associated with Joubert Syndrome 9 (JBTS9), a rare ciliopathy characterized by cerebellar ataxia, oculomotor apraxia, hypotonia, breathing difficulties, abnormal eye and tongue movements, intellectual disability, and brain anomalies. Mutations in the gene have also been linked to Meckel Syndrome 6 (MKS6), a ciliopathy with a more severe phenotype compared to JBTS. The autosomal recessive disorder is characterized by occipital encephalocele, large cystic kidneys, fibrotic changes in the liver and polydactyly. COACH syndrome is another disorder that is related to the CC2D2A gene. The disease, which has overlapping features with JBTS and MKS, is characterized by cerebellar vermis hypo/aplasia, oligophrenia, ataxia, ocular coloboma, and hepatic fibrosis.