CFC1B is an EGF-CFC family member involved in developmental signaling pathways. Based on limited published evidence, CFC1B functions in nodal signaling and binds activin receptors, playing roles in anterior/posterior pattern specification, left/right symmetry determination, heart development, and blood vessel formation. The protein localizes to the cell surface and extracellular region. CFC1B promoter methylation status shows significant correlation with mRNA expression levels and has been associated with Tetralogy of Fallot, a congenital heart defect 1, suggesting epigenetic dysregulation may contribute to cardiac developmental abnormalities.