The mRNA levels of Atf4 and its target genes involved in muscle atrophy, i.e., Trib3, Cdkn1a, and Eif4ebp1, were higher during HS in both H2O- and HF-treated mice (Figure 2E–H), while the mRNA levels of the ATF4-regulated atrogene Gadd45a remained unchanged (Figure 2I). The gene discussed is GADD45A; the disease is hydrops fetalis.