HOXC13 and hydrops fetalis: Analyzing genes in our data sets known to be associated with HF and IFE structure and function, stem cell markers and immune function, we found that, in anagen, the hair cycle-associated genes that are most upregulated are MSX2, FOXN1 and HSD17B14, and the most significantly differently expressed genes associated with HF structure (apart from keratins) is HOXC13. It has been suggested previously that FOXN1 and HOXC13 are required for hair keratin expression in mice and humans [96,97] and HOXC13 was also shown to be highly expressed in human anagen HFs [97].