At E17.5 and E18.5, Lrig1 expression was upregulated in the P-cadherin dim population of multipotent stem cells in the developing HF (Nowak et al., 2008) and was absent from the P-cadherin bright cells at the base (Figures 1A, S1B, and S1F–S1H). The gene discussed is LRIG1; the disease is hydrops fetalis.