Several of HF and PHR subdivisions, in particular, SUB, PrS, PaS, and MEC share connectivity with the retrosplenial cortex (RSC; Finch, Derian, & Babb, 1984; Agster & Burwell, 2009; Honda, Furuta, Kaneko, Shibata, & Sasaki, 2011; Honda & Ishizuka, 2015). This evidence concerns the gene MYCBP2 and hydrops fetalis.