Similar anomalies with selective immunodeficiencies and growth restriction have also been described in patients with hypomorphic mutations in GINS1 and a N-terminal truncation of MCM4 (not affecting MCM2–7 chromatin levels), which suggests a common pathogenetic mechanism affecting initiation of DNA replication (Cottineau et al., 2017, Gineau et al., 2012, Hughes et al., 2012). Here, MCM2 is linked to Immunodeficiency.