Point mutations in FAM111A, a putative host restriction factor that has been linked to DNA replication via a PCNA‐binding PIP box (Fine et al, 2012; Alabert et al, 2014; Tarnita et al, 2019), give rise to the two phenotypically related disorders gracile bone dysplasia and Kenny–Caffey syndrome, which manifest with a broad spectrum of severe growth abnormalities including thin and brittle bones, dwarfism, facial dysmorphism, and splenic hypoplasia (Unger et al, 2013; Isojima et al, 2014; Nikkel et al, 2014). The gene discussed is FAM111A; the disease is osteocraniostenosis.