Based on limited published evidence, CCDC138 encodes a coiled-coil domain-containing protein. Proteomic analysis identified CCDC138 as a novel cilia basal body/centriolar satellite protein 1, suggesting a role in ciliary structure or function. CCDC138 is located within the smallest region of overlap (249 kb) of the 2q12.3q13 microdeletion associated with developmental delay, microcephaly, growth retardation, behavioral problems, and skeletal anomalies 2, though RANBP2 was identified as the primary neurological candidate. Direct molecular functions remain largely uncharacterized.