NSD1 and Sotos syndrome: The macrocephaly phenotype associated with NSD1 mutations in Sotos syndrome has variable penetrance as 72–95% of patients present with larger head circumference (Cecconi et al., 2005; Faravelli, 2005; Saugier-Veber et al., 2007; Fortin et al., 2021; Muhsin et al., 2022).