For example, missense variants in the DH domain of FGD1 cause Aarskog–Scott syndrome (Orrico et al., 2004; Pérez-Coria et al., 2015), while the DH domain variants in FGD4 lead to Charcot–Marie–Tooth disease type 4H (CMT4H) (Hyun et al., 2015). This evidence concerns the gene FGD4 and faciodigitogenital syndrome.