A recent study focussing on fetal malformations detected in utero identified a case of non‐immune hydrops fetalis with a homozygous variant in LZTR1. 34 Fetal hydrops was also observed in 4 non‐liveborn siblings described by Johnston et al.15 Together with siblings of O1409410/O1409412, these results indicate that LZTR1 mutations can result in a much more severe form of disease. The gene discussed is LZTR1; the disease is hydrops fetalis.