At this time, our observations in P10 HFs in which H3.3 abundance is reduced in HIRA KO compared to HIRA WT indicate that HIRA's role in the melanocytic lineage is likely connected to H3.3, and that DAXX, another H3.3 histone chaperone (Choi et al. 2024), does not compensate for HIRA loss. This evidence concerns the gene HIRA and Hand-foot syndrome.