Gene Ontology (GO) enrichment analysis (Biological Process) of these Titan-specific RDD genes revealed an association with several biological processes, including metabolic regulation (Kat2a, Sfrp5, Agpat4, and Hcrt), growth factor signaling (Stat3, Stat5a, Stat5b, and Igf2r), skin differentiation and immune regulation (Table 1). Here, AGPAT4 is linked to sinus histiocytosis with massive lymphadenopathy.