GGCX and complement factor I deficiency: This notion is reflected by observations that not all patients with GGCX variants have vitamin K-dependent coagulation factor deficiency (De Vilder et al., 2017), which functional studies could explain that distinct variants in the GGCX gene can reduce the corresponding carboxylase activity to a different degree in different substrates (Tie et al., 2016; Hao et al., 2021; Rishavy et al., 2022; Ghosh et al., 2021).