Fam20a, Family with Sequence Similarity 20, Member A, is a pseudo-kinase. It binds to FAM20C (the Golgi casein kinase) and potentiates its function to phosphorylate secreted proteins crucial for biomineralization. This function is vital for processes like amelogenesis and maintaining pulp tissue homeostasis, preventing ectopic mineralization in soft tissues [1].

Gene knockout mouse models have provided valuable insights. In Sox2-Cre;Fam20afl/fl mice, Fam20a ablation in both dental epithelium and mesenchyme led to an enamel phenotype resembling human amelogenesis imperfecta associated with FAM20A mutations, but no apparent dentin defects. Secretory-stage ameloblasts were abnormal, and enamel-matrix-protein-encoding genes were downregulated [2]. Epithelial-specific deletion of Fam20a in mice caused short root defects, with irregular breaks in the epithelial root sheath, initiation of the WNT signaling pathway, and decreased expression of Cdc42. It also affected the intraosseous eruption phase of tooth emergence, delaying osteoclast peak and tooth eruption [3].

In conclusion, Fam20a is essential for amelogenesis and tooth root development, playing a key role in maintaining the normal structure and function of dental tissues. The study of Fam20a using gene knockout mouse models has enhanced our understanding of its functions in these processes and its association with diseases such as enamel-renal syndrome, amelogenesis imperfecta, and short root defects [1,2,3].